Lemon Blueberry Ice-Cream Cake

Preheat oven to 350 °F. Butter a 9-inch round cake pan (2 inches deep) and line bottom with a round of wax paper. Into a bowl sift together flour, baking powder, and salt. In a large bowl with an electric mixer beat together butter and 1 cup sugar until light and fluffy, about 1 minute. Separate eggs and beat yolks 1 at a time into butter mixture, beating well after each addition. In 3 batches alternately beat in flour mixture and milk, beginning and ending with flour mixture. Add zest and 2 tablespoons lemon juice, beating until just combined (do not overbeat). In a bowl with cleaned beaters beat whites until they hold soft peaks and beat in remaining 1/4 cup sugar. Fold whites into batter gently but thoroughly. Transfer batter to cake pan and bake in middle of oven until a tester comes out clean, 35 to 40 minutes. Cool cake in pan on a rack and invert onto rack. Cake may be prepared up to this point 1 day ahead and kept in an airtight container at cool room temperature.