Let the roll soak in the water and then squeeze it out well!
Peel the onion and cut into fine cubes.
Mix the minced meat with the squeezed out bun, the onion and the egg well. Then add the creme fraiche and the butter vegetables to the mince.
Grease the baking dish and add the mince. Sprinkle the grated cheese on top and bake the whole thing in a preheated oven at 200 degrees for about 40 minutes.