Orange Caraway Seed Cakes

Preheat the oven to 325 °F. and butter and flour eighteen 1/3-cup brioche or muffin tins. Into a bowl sift together the flour, the baking powder, the salt, and the baking soda and stir in the caraway seeds. In another bowl with an electric mixer cream the butter with the granulated sugar until it is light and fluffy, beat in the eggs, 1 at a time, beating well after each addition, and beat in the zest and the vanilla. Add the flour mixture to the egg mixture alternately with the sour cream in batches, beginning and ending with the flour mixture and beating the batter after each addition. Divide the batter among the tins, arrange the tins in a jelly-roll pan, and bake the cakes in the middle of the oven for 25 to 30 minutes, or until a tester comes out clean. Let the cakes cool in the tins for 3 minutes, turn them out onto a rack, and let them cool completely. The cakes may be made 2 days in advance and kept in an airtight container. Dust the cakes with the confectioners' sugar just before serving.