Baked good layers: Preheat stove to 375 degrees with racks in upper and lower thirds. On a delicately floured surface, carry out one piece of cake batter into a 9-inch round, somewhat under 1/8 inch thick. Move to a material lined baking sheet. Rehash with residual batter, putting 1 or 2 rounds on each sheet. Brush with beaten egg and sprinkle liberally with sanding sugar. Prepare, pivoting sheets partially through, until brilliant brown and fresh, 22 to 24 minutes. Let cool totally on sheets on wire racks.
Filling: Whisk together granulated sugar, cornstarch, and salt in a medium pot. Whisk together milk and egg yolks in a bowl, then add to skillet alongside margarine. Cook over medium intensity, whisking continually, until blend reaches boiling point. Keep on cooking 1 moment, whisking, then, at that point, eliminate from intensity and mix in vanilla. Strain blend through a fine sifter into a bowl. Cover with cling wrap, squeezing it straightforwardly onto surface. Refrigerate somewhere around 2 hours and as long as 2 days.
Whisk weighty cream to firm pinnacles. Whisk cake cream to relax. Overlay in whipped cream, then berries.
Spread 1/4 cup jam on a cake layer. Top with 33% of cake cream blend (around 1 1/4 cups), then a subsequent baked good layer. Rehash with outstanding jam, cream blend, and cake, finishing with baked good. Wrap with saran wrap and refrigerate, short-term and as long as 2 days. Serve, finished off with whipped cream and more berries.