Napoleon cake with custard

I haven't found my Napoleon recipe yet. I tried baking from ready-made puff pastry, from ready-made cake layers, and made a “wet napoleon.” Today I have a new experiment. I'm pleased with the result. The cake turned out delicious, moderately sweet, with a lot of layers. The cream soaked the cakes very well, they “stick together” into a single piece.
Adjust servings in the full version
First I make the cream. While it’s cooling, I just have time to bake the cakes.
Place eggs and sugar in one bowl. The amount of sugar can be adjusted to your taste. I sprinkled on one and a half glasses. It seemed optimal to me. But the men said it was not sweet. Next time I'll add 2 cups.
Place the saucepan with the milk-egg mixture over medium heat. After some time, the cream will begin to thicken little by little. Cook until the first, lazy glops appear on the surface. It took me a little less than 15 minutes. Do not forget to actively work with the whisk all the time. The cream sticks to the bottom very quickly.
Once thickened, remove the custard from the heat and immediately stir in the butter until melted. Cover and leave to cool.
Roll each piece as thinly as possible; I can see the pattern of my work surface through the dough. It rolls easily. I roll directly on baking paper and bake it on the same sheet.
The cakes bake very quickly: 5-6 minutes and you’re done. I bake on 2 baking sheets at once in fan mode. While one batch is baking, I just have time to roll out the next one. I don’t level the cakes before baking. They still bend in the oven.
The cakes turn out to be very thin and very fragile. I put them in a little pile. It took me just over an hour to roll out and bake.
When all the cakes are ready and the cream has cooled completely, we begin to assemble the cake. I find it convenient to make it in a springform pan. In this case, the cake turns out perfectly round and excess cream does not leak out anywhere. I put 3 tablespoons of cream on each cake. From time to time I lightly press the cakes on top.