- 8 ounces unsalted butter, at room temperature
- 2 cups sugar
- 1 1/2 tablespoons finely grated fresh orange peel
- 4 large eggs, at room temperature
- 2 teaspoons baking powder
- 1 teaspoon baking soda
- 1/4 teaspoon salt
- 1 tablespoon pure vanilla extract
- 4 cups flour
- 2 cups sour cream, at room temperature
- Preheat the oven to 350 degrees F. Grease a 9-by-3-inch round springform pan and a 6-by-3-inch round springform pan.
- Using an electric mixer, cream the butter, sugar and orange peel at high speed until fluffy, about 5 minutes, scraping down the sides occasionally. Add the eggs one at a time, beating well after each addition. Mix in the baking powder, baking soda and salt and mix at medium speed, then mix in the vanilla. Add 2 cups flour and 1 cup sour cream and mix at low speed until barely blended. Repeat with the remaining 2 cups flour and 1 cup sour cream.
- Spoon the batter evenly into the prepared cake pans, filling them about half full. Bake until the cakes are deep golden and a toothpick inserted into the center comes out clean, about 1 hour and 10 minutes.
- Transfer the pans to a rack to cool for 20 minutes, then remove the sides of the pans and let the cakes cool completely.