Caramelized Onion Tart with Swiss Cheese and Ham
This caramelized onion tart combines slowly cooked onions, Swiss cheese, savory ham or prosciutto, fresh herbs, and a creamy egg filling inside a crisp, flaky pie crust. Inspired by the French tarte à l’oignon, it’s a simple savory tart that works beautifully for brunch, lunch, or a light dinner.
The onions are cooked until soft, golden, and naturally sweet before being combined with cheese, herbs, eggs, and cream. Using a store-bought pie shell keeps the recipe approachable while still delivering the rich, comforting flavors you’d expect from a homemade savory tart.
Serve it warm with a simple green salad, roasted vegetables, or enjoy a slice on its own.
Why You’ll Love This Caramelized Onion Tart
- The onions are the star. Slowly cooking the onions brings out their natural sweetness and gives the tart a rich, savory flavor.
- Creamy, salty, and slightly sweet flavors work together. Swiss cheese, ham or prosciutto, caramelized onions, and fresh herbs create plenty of flavor without requiring a long ingredient list.
- A store-bought crust keeps things simple. You get the comfort of a homemade savory tart without having to make pastry from scratch.
- It works for several meals. Serve it for breakfast or brunch, pair it with a salad for lunch, or turn it into an easy light dinner.
- It’s easy to customize. Change the cheese, leave out the meat, experiment with herbs, or use different varieties of onions depending on what you have.
- It reheats well. Leftover slices make an easy meal the next day.
Ingredients Breakdown
- Onions – The star of the dish! Slow-cooked to perfection, they become sweet and caramelized, adding depth of flavor.
- Butter & Brown Sugar – Butter adds richness, while a small amount of brown sugar enhances the sweetness and browning of the onions.
- Swiss Cheese – Mild and creamy, Swiss cheese balances the saltiness of the ham or prosciutto.
- Prosciutto or Ham – Adds a salty, savory contrast to the sweet onions. Feel free to substitute with turkey or bacon for a different twist.
- Thyme & Basil – These herbs complement the onions beautifully, adding an aromatic touch.
- Eggs & Heavy Cream – Helps create a rich, custard-like filling that holds everything together.
- Pre-made Pie Shell – A convenient choice that fits perfectly in most pie dishes and cuts down on prep time.
What Are the Best Onions for an Onion Tart?
Yellow onions are an excellent all-purpose choice for this recipe because they develop a deep, savory sweetness as they cook. Sweet onions can also be used if you prefer a milder, slightly sweeter filling.
White onions have a sharper flavor and can work, although the finished tart may taste a little less sweet. Red onions are another option, but they will change both the color and flavor of the filling.
Whichever variety you choose, the most important step is giving the onions enough time to soften and develop flavor. Cook them gently rather than trying to brown them quickly over high heat.
Don’t Rush the Onions
Caramelized onions need time. Cooking them slowly allows moisture to evaporate while their flavor becomes sweeter and more concentrated.
If the heat is too high, the edges can burn before the onions have softened. Keep the heat moderate to low and stir periodically until the onions are soft and golden.
Making Pie Dough from Scratch: Pros & Cons
Pros:
- Homemade dough has a richer, butterier taste compared to store-bought versions.
- You can control the ingredients, ensuring there are no preservatives or artificial flavors.
- Customizable—add herbs or spices for extra flavor.
Cons:
- It is time-consuming and requires chilling time.
- It can be tricky to get the right consistency, especially for beginners.
- It requires extra effort to roll out and shape the dough.
If you have the time and enjoy making pastry from scratch, it’s a rewarding process. However, for convenience, a quality store-bought crust is a great alternative.
Why Use a Store-Bought Pie Shell?
While homemade dough can be delicious, it’s time-consuming and requires extra effort. A store-bought frozen pie shell is an excellent alternative because:
- It’s already shaped to fit a standard pie dish, making baking easier.
- Saves time without compromising on taste.
- Provides a perfectly flaky and crispy texture.
If you love making dough from scratch, go for it! But for busy days, a pre-made crust is your best friend.
Cooking & Baking Tips
- Choose Fresh Onions – Select onions that are firm and free of soft spots. Avoid any that have started sprouting.
- Caramelizing Onions – Cook them low and slow to bring out their natural sweetness without burning.
- Cheese Selection – If using a more pungent cheese, reduce the amount of ham or prosciutto to balance the flavors.
- Preventing a Soggy Crust – Pre-bake (blind bake) your pie shell for a few minutes before adding the filling to ensure a crispy base.
- Baking Evenly – Place the tart in the center of the oven and rotate halfway through for even cooking.
- Covering the Edges – If the crust starts to brown too quickly, cover the edges with aluminum foil to prevent burning.
Pairing, Variations & Storage
Pairing Suggestions:
- Serve warm or at room temperature with a simple tossed green salad dressed with olive oil and balsamic vinegar.
- Pair with a crisp white wine like Sauvignon Blanc or a light-bodied red like Pinot Noir.
- If serving for brunch, a glass of sparkling wine or fresh orange juice is a lovely addition.
Onion Tart Variations
Gruyère Onion Tart
Replace Swiss with Gruyère for a stronger nutty flavor.
Meatless Onion Tart
Leave out the ham/prosciutto and increase the herbs.
Herb Onion Tart
Use thyme, parsley, chives, or scallions.
Storage Tips:
- Store leftover Onion Tart in an airtight container in the refrigerator for up to 3 days.
- Reheat in the oven at 350°F for about 10 minutes or until warm.
- You can also freeze it! Wrap slices tightly in plastic wrap and store in a freezer-safe bag for up to 2 months. Thaw and reheat before serving.
Frequently Asked Questions
What type of onion is best for an onion tart?
Yellow onions are a great choice because they become sweet and flavorful when cooked slowly. Sweet onions also work well if you prefer a milder flavor.
Do I have to caramelize the onions before making the tart?
Yes. Cooking the onions before adding them to the tart removes excess moisture, softens their texture, and develops their flavor. Adding raw onions directly to the filling would produce a very different result.
Can I make onion tart without ham or prosciutto?
Yes. Leave out the ham or prosciutto for a meatless version. You may want to adjust the salt slightly because the cured meat contributes saltiness to the original recipe.
What cheese goes well with caramelized onions?
Swiss cheese works particularly well in this recipe because of its mild, nutty flavor. Gruyère is another excellent option and gives the tart a stronger, more pronounced flavor.
How do I keep an onion tart from becoming soggy?
Cook the onions thoroughly so excess moisture evaporates, and partially bake the pie crust before adding the filling. These two steps help the crust stay crisp underneath the creamy filling.
Can I make onion tart ahead of time?
Yes. You can prepare the caramelized onions ahead and refrigerate them until you’re ready to assemble the tart. The baked tart can also be refrigerated and reheated before serving.
How do I reheat leftover onion tart?
Reheat individual slices in a 350°F oven until warmed through. The oven is preferable to the microwave when you want to maintain a crisp crust.
What should I serve with onion tart?
A simple green salad is one of the easiest pairings. You can also serve the tart with roasted vegetables, soup, or a fresh vegetable salad for a light lunch or dinner.
Final Thoughts
This Onion Tart is a true gem in French-Caribbean cuisine. It’s simple, flavorful, and versatile, making it perfect for any time of day. Fresh chives also make an excellent finishing herb. Sprinkle chopped chives over the tart just before serving for mild onion flavor and a fresh pop of color.
Whether you’re preparing it for a special occasion or need a quick and delicious meal, this recipe is a must-try. So, grab your ingredients and make this delightful tart today!
Caramelized Onion Tart
Equipment
- 9-inch pie or tart pan
- Large Skillet
- Wooden spoon or silicone spatula
- Measuring cups and spoons
- Baking sheet — optional, for placing under the tart while baking
Ingredients
For the Filling:
- 4 onions finely sliced (about 4 cups)
- 4 tablespoons butter
- 1 tablespoon light brown sugar
- ¾ cup heavy cream
- 1 cup Swiss cheese grated
- 6 ounces prosciutto or regular ham sliced
- 2 teaspoons fresh thyme leaves
- 1 teaspoon dried basil
- 2 eggs beaten
- Salt and freshly ground black pepper to taste
- 1 pre-made 9-inch frozen pie shell
For Homemade Pie Dough (Optional):
- 1 ½ cups all-purpose flour
- 3 ½ ounces unsalted butter chilled and chopped
- 1 egg yolk
- 1 –2 tablespoons water
Instructions
If Making the Dough from Scratch:
- Sift the flour into a mixing bowl. Add butter and pulse in a food processor until the mixture resembles fine breadcrumbs.
- Gradually add the egg yolk and water, mixing until the dough forms. Gently press it into a ball—do not knead. Wrap in plastic and chill for 20 minutes.
Prepping the Pie Shell:
- Preheat oven to 375°F (190°C).
- If using homemade dough, roll it out on a floured surface and gently place it into a 9-inch pie tin. Trim any excess dough.
- Line the shell with baking paper and add baking beads or dried beans. Bake for 15 minutes, remove weights and paper, then bake for another 5 minutes. Let cool.
Making the Filling:
- Melt butter in a large pan over low heat. Add onions and cook for 20–25 minutes, stirring occasionally until softened.
- Add brown sugar and continue cooking for another 15 minutes, stirring frequently until caramelized. Remove from heat.
Assembling & Baking:
- In a bowl, beat eggs and mix in heavy cream, thyme, basil, and grated cheese. Stir in the prosciutto or ham.
- Add the caramelized onions to the mixture and season with salt and black pepper to taste.
- Pour the filling into the pre-baked pie shell.
- Bake on the middle rack for 40 minutes, or until golden brown and fully set. If the crust browns too quickly, cover edges with aluminum foil.
- Let cool slightly before serving.
Serving Suggestions:
- Serve warm or at room temperature with a green salad.
- Store leftovers in the fridge for up to 3 days, or freeze for up to 2 months.
- Enjoy this simple yet elegant Onion Tart!
Notes
Pairing & Storage
Pairing Suggestions:- Serve warm or at room temperature with a simple tossed green salad dressed with olive oil and balsamic vinegar.
- Pair with a crisp white wine like Sauvignon Blanc or a light-bodied red like Pinot Noir.
- If serving for brunch, a glass of sparkling wine or fresh orange juice is a lovely addition.
- Store leftover Onion Tart in an airtight container in the refrigerator for up to 3 days.
- Reheat in the oven at 350°F for about 10 minutes or until warm.
- You can also freeze it! Wrap slices tightly in plastic wrap and store in a freezer-safe bag for up to 2 months. Thaw and reheat before serving.
Nutrition
Please keep in mind that nutritional information is a rough estimate and can vary greatly based on the products used.
Nutrition info is automatically generated and provided as a courtesy and as an estimate only.
Corn Allergy:
Always choose ingredients without corn or corn derivatives.
Originally July 19, 2015 and re-published March 20, 2025. Updated August 11, 2026, with expanded recipe tips, ingredient information, serving suggestions, and FAQs.
