Make this delicious trifle as is, or substitute chocolate pudding for the vanilla custard, chocolate cake for the vanilla cake, or any other flavor combination that inspires you. Shelley uses the orange cake recipe from The Silver Palate Cookbook (Workman Publishing)–but you can substitute any favorite single-layer-cake recipe, or use store-bought pound cake.
Pour milk into a small saucepan and set over medium-high heat. In a heavy-bottomed 3- to 4-quart saucepan over a cold burner, whisk ¾ cup sugar into egg yolks, and beat 2 to 3 minutes until pale yellow. Add flour and whisk until combined.
When milk comes to a low boil, add it slowly to egg mixture, whisking as you go. Now light the burner under the egg mixture to medium-high and continue whisking. After custard comes to a low boil, reduce heat to medium-low and continue whisking until thickened, 2 or 3 more minutes. Remove from heat and beat in butter and vanilla. Set aside.
While custard is cooling, prepare whipped cream and cake: Beat cream with remaining tablespoon sugar until it forms medium peaks. Set aside. Halve the cake crosswise and spread the middle with jam. Cut cake lengthwise into strips, then widthwise, into 1-inch squares.
Assemble the trifle: Pool one-third of the cooled custard in the bottom of a 14-cup trifle bowl or other glass serving bowl. Arrange cake pieces around the outside (layers visible); then fill in the middle. Repeat once, first with custard, then with cake; then top with remaining third of custard, followed by whipped cream. Garnish with berries, nuts, mint leaves, or other edible decorations.