Apple and Blackberry Cake with Bushmills Custard Sauce

FOR THE CUSTARD SAUCE:
Bring milk to simmer in heavy 1 1/2-quart saucepan. Whisk sugar and yolks in large metal bowl to blend. Gradually whisk in hot milk. Return mixture to saucepan and stir constantly over medium-low heat until custard thickens and coats back of spoon, about 6 minutes (do not allow custard to simmer). Transfer custard to clean bowl. Whisk in whiskey and vanilla. Cool slightly. Cover and refrigerate until cold, about 2 hours. Makes about 2 cups.

FOR THE CAKE:
Preheat oven to 350 degrees F.

Butter 10-inch springform pan. Line pan with parchment paper; butter paper. Using electric stand mixer and paddle attachment, beat butter and sugar in large bowl until light and fluffy. Beat in eggs on high speed one at a time. Add flour alternately with milk, beating just until blended. Stir in diced apples. Fold in blackberries. Transfer batter to prepared pan. Arrange apple slices over top of cake, overlapping neatly.

Bake cake until lightly browned and skewer inserted near center of cake comes out clean, about 1 hour, 15 minutes. Cool in pan 10 minutes.

Melt jam in heavy small saucepan over medium heat. Strain jam; discard solids. Brush jam over top of cake.

DO-AHEAD TIP:
Sauce and cake can be made 1 day ahead. Keep sauce refrigerated. Cover cake with foil and store at room temperature.

Spoon custard sauce onto plates. Cut cake into wedges. Transfer wedges to plates and serve.