1 stick butter at room temperature
3/4 cup granulated sugar
1 tsp finely grated citrus zest (orange, lemon or lime)
2 large eggs, separated
1 1/2 cup all purpose flour
1/2 tsp baking powder
1/4 tsp salt
1/4 cup milk
6 Tbsp jam or preserves
1 cup confectioners sugar
1/4 cup freshly squeezed citrus juice (orange, lemon or lime)
Preheat oven to 350 degrees. Grease a standard 6 cup muffin tin and set aside.
In a medium bowl, beat butter, granulated sugar and zest until light and fluffy. Beat in egg yolks one at a time until creamy, set aside. Sift together flour, salt and baking powder. Add flour mixture and milk in alternating batches to butter mixture and set aside.In a clean bowl, whisk egg whites to soft peaks; fold into batter. Divide half the batter into six muffin tins. Make an indentation in the middle of each; fill with 1 Tbsp of jam. Top each with remaining batter and smooth tops down. Bake until cake tester inserted in top cake layer comes out clean, about 30 minutes. Unmold cakes and transfer them to a wire rack to cool completely.In a small bowl, whisk together confectioners sugar and juice. Place rack over wax paper and drizzle cakes with glaze. Makes 6 individual cakes.