Quickly knead a dough from the flour, butter, egg yolk and milk and put it in a cool place.
Preheat the oven to 175 ° C.
Cut out six large circles 10cm in diameter and 3mm high from the dough, place each in a small tart dish, prick with a fork and bake blind for 10 minutes.
Mix the crème fraîche, egg yolk, vanilla sugar and powdered sugar, after the 10 minutes distribute on the tart cases and bake in 15 minutes.
Let it cool down a bit and sprinkle some brown sugar on each tart and crust it brown with the flame.