Cut the chicken breast fillet lengthways. Wash, dry and sprinkle with lemon juice on both sides and pepper.
Roughly dice the toast and cheese and chop together in a blender.
Fry the fillets in melted clarified butter for 1/2 minute on each side, season with salt and place in an ovenproof dish. Sprinkle with lemon peel. Spread the bread and cheese crumbs evenly over the top. Spoon the crème fraîche on the surface. Cover with flakes of butter.
In a preheated oven at 220 ° C top / bottom heat, crust over golden brown in 15 - 20 minutes.