Preheat oven to 350 degrees Fahrenheit. In a mixer bowl, whip the butter and sugar to a cream.
Add the eggs one at a time and missing well after each addition. Add the orange zest, then the sifted flour with the baking powder alternating with the orange juice. Add the vanilla extract and the rum. Mix well and on high speed for about 1 minute.
Pour the cake batter into a buttered and floured 10 inch pan or 10 inch tin tube. Bake in the oven for 40 minutes or when a cake tester or a toothpick inserted comes out clean.
Remove the cake from the oven, and let cool covered with a kitchen towel. Remove from pan, dust with powdered sugar and serve.
Use Rum Barbancourt, homemade vanilla extract and organic sugar preferably.