Step 1In a mixer, whisk together the egg yolks, sugar, cornstarch and vanilla seeds. Slowly add the buttermilk, whisking to combine.
Step 2Place the bowl over a saucepan of simmering water and heat the mixture, whisking until it thickens.
Step 3Return the bowl to the mixer and mix until the mixture has cooled to lukewarm. Beat in the butter and Grand Marnier. Strain through a fine sieve. Place in a bowl, cover with plastic wrap and refrigerate until completely cooled.
Step 1Heat the oven to 325 degrees. Using a mixer with the paddle attachment, cream together the butter and sugar. Beat in the eggs one at a time and then add the vanilla.
Step 2In a separate bowl, sift together the flour, baking powder, soda and salt.
Step 3Add half the buttermilk to the creamed mixture and mix well. Add half the dry ingredients, then the remaining buttermilk and mix. Add the remaining dry ingredients and mix.
Step 4Line a 13- by 9-inch baking pan with parchment and spray with nonstick spray. Spread the batter in the pan. Bake at 325 degrees for 16 to 25 minutes until a wooden pick comes out clean. Cool slightly, then remove the cake from the pan and cool completely before cutting.
Step 5Using a cookie cutter, cut the cake into 12 (2- to 3-inch) rounds, selecting a size that fits snugly into the glasses you'll layer the trifles in.
Step 1Clean the berries and dice into half-inch pieces. In a saucepan, cook the berries with 4 tablespoons sugar over medium heat, stirring occasionally, until tender and a syrup has formed, about 3 minutes.
Step 2Taste and add the remaining sugar if needed. Add the Grand Marnier. Remove the compote from the heat, transfer it to a bowl and cool completely. Makes about 2 cups.
Step 1Combine the sugar and water in a small saucepan and bring to a boil. Remove it from the heat and let it cool completely, then add the Grand Marnier. Makes about three-fourths cup.
Step 1In a large bowl, work the pastry cream with a spatula until softened, then fold in the whipped cream.
Step 2In each of 6 (8-ounce) Pilsener glasses, place 1 teaspoon strawberry compote, then, using a pastry bag with no tip, or a spoon, add a half-inch layer of pastry cream. Brush each cake round with the sugar syrup. Place one round in each glass on top of the cream. Add a layer of sliced strawberries.
Step 3Repeat the layering of compote, cream and cake. Finish with cream and top with more strawberry slices.