TIPSY CAKE

Steps:

• Make frosting:
• Bring milk and cream just to a boil in a 3-quart heavy saucepan and remove from heat. Whisk together yolks, sugar, cornstarch, and a pinch of salt in a bowl and add hot milk mixture in a slow stream, whisking constantly. Pour custard into pan and boil, whisking, until thick and smooth, about 1 minute. Force custard through a fine sieve into a bowl. Set bowl of custard frosting in a larger bowl of ice and cold water, then cool, stirring occasionally, until cold. Chill frosting, its surface covered with plastic wrap to prevent a skin from forming, 2 hours.
• Make cake layers:
• Preheat oven to 350°F. Butter 2 (8- by 2-inch) round cake pans and line bottoms with wax paper. Butter paper and dust with flour, knocking out excess. Sift together 1 1/2 cups cake flour, baking powder, and salt. Beat together butter, sugar, and vanilla in a large bowl with an electric mixer until light and fluffy. Add eggs, 1 at a time, then yolk, beating well after each addition. With mixer on low speed, alternately add milk and flour mixture in 4 batches, beginning and ending with milk (mixture will look curdled; do not overbeat).
• Divide batter between cake pans, smoothing tops. Bake in middle of oven until pale and a tester comes out clean, about 20 minutes. Run a thin knife around edges of pans and invert layers onto a rack. Carefully remove wax paper and cool layers completely.
• Assemble cake:
• Halve cake layers horizontally with a long serrated knife. Arrange 1 cake half, cut side up, on a plate and brush with 2 tablespoons Sherry. Spread evenly with 3 tablespoons jam. Repeat with remaining 3 layers, ending with a layer cut side down. Brush top with Sherry. Frost cake with custard.