Preheat oven to 400 degrees (175 C).
Pre-bake the piecrust for 15 minutes.
Stir the crème fraîche soft. Cut the vanilla been lengthwise and scrape out the seeds and mix into the crème fraîche. Make sure you mix well. Add sugar. Separate egg yolks from the whites and add the egg yolks to the crème fraîche mixture.
Add the berries to the pie crust and pour over the crème fraîche mixture. Bake it in the oven on 175 C for 30 minutes. To garnish, add some fresh berries on top of the tart.