1/2cupraspberry preserves— (or any fruit preserves)
For the cake:
Preheat Oven to 350˚F. Line bottoms of a 9″ cake pan with parchment paper, lightly spray with cooking spray on top of the paper and the sides of the pans.
In the bowl of a stand mixer fitted with the whisk attachment, beat eggs on medium speed and slowly add the sugar. Continue beating on high speed for 8 minutes until light and thick. we need the egg sugar mixture to be very fluffy.
In a bowl combine flour and baking powder.
Add flour mixture to the eggs and using a rubber spatula, fold flour into the eggs. This step is tricky, make sure there are no thick pockets of flour. Keep scraping the sides and bottom of the bowl. Do not over mix. Stop folding, when there are no pockets of flour.
Pour batter into a pan and bake for 25-30 minutes, until golden.
Remove from the pan, using a knife to loosen the cake. Let it cool on a cooling rack.
Using a serrated knife, carefully cut cake into two thin layers through the middle.
For the pastry cream:
In a bowl, combine 4 tablespoons of the granulated sugar, the egg yolks, the flour, and the salt. Set aside.
Heat the milk and the remaining in a small saucepan over medium-high heat. Bring to a boil and remove from the heat. Add the vanilla extract and cool for 2 minutes.
Gradually add the warm milk to the egg yolk mixture, whisking constantly.
Return the mixture to the saucepan over medium-low heat and whisk constantly until the mixture thickens and comes to a boil. It may take from 2 to 6 minutes. It needs to be thick.
Cool completely at room temperature. You can place the bowl over a bowl filled with ice, to speed up the cooling process.
Beat 1 cup of heavy cream and 1 tbsp sugar with a mixer until stiff peaks.
Fold the whipped cream into the cooled custard. Use immediately, or cover with plastic wrap and store in the fridge.
To assemble the cakes in a jar:
Add lemon juice to the simple syrup.
Using a round cutter like this, cut circles out of the cake layers. We need 3 circles for each cake in a jar.
Place one round of cake on the bottom of each jar. Brush with simple syrup. Spread raspberry preserves.
Add about 3 tbsp pastry cream (or more). Repeat with 2 more cake rounds per jar, until you use them all, finishing with pastry cream for each cake in a jar.
Refrigerate for at least 30 minutes.
Store in the fridge for up to a week, or freeze (each jar needs to be with a sealed lid) for up to 1 month. If using cake mix, you need to either use half of it for 6 cakes in a jar, or make more pastry cream and make more cake jars.