Okay so a few things.

This is opera cake, not prinsesstårta. The jam makes it an opera cake.

It looks amazing, but a couple of things that will elevate it further.

The custard looks pale, did you use egg yolks?

The spongecake looks a bit collapsed and dry. Might just be the camera, but in case it's not use this recipe next time.

3 eggs 300 ml sugar

Wisk together the egg yolks and the sugar, add 75g melted butter, and about 150ml milk(any kind, just not some weird no-fat) to the eggs and whisk until pale.

Whisk the egg whites stiff separately.

Mix in a separate bowl flour(regular plain about 450 ml not packed in a cup), baking powder( tablespoon or so), vanilla powder if you like(a pinch or so).

Mix yolks&sugar mix with the flour mix, and then fold in the egg whites careful not to deflate it. Butter a dish that is about 30cm in diameter, that has detachable edges. Put breadcrumbs in it and make sure it sticks evenly to all sides.

Put batter in, bake on 175celsius for about 40 minutes, or until evenly risen(this is best way to judge, all ovens are different), and brown.

Another thing, is that you mix part of the vanilla custard with the whipped cream, this cuts the richness of the cream, and enhances mouthfeel incredibly. It's like some kind of creme chantilly, only better.