Peel, wash and cut the potatoes into pieces. Cook in boiling salted water for about 20 minutes. Wash the meat, dab dry and season with salt and pepper. Heat 2 tablespoons of oil in a frying pan, fry the chicken fillets all around, remove.
Set the pan aside. Wash the herbs, dab dry and chop except for a few stems of chervil. Put half the parsley aside. Cut the crust off the white bread. Finely grate the bread. Mix bread crumbs and herbs and spread on the chicken fillets.
Add butter in small flakes. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Drain the potatoes, add milk and mash into puree.
Stir in the remaining parsley and season with salt and pepper. Wash the tomatoes and grate them dry. Heat the pan with the frying fat, add 1 teaspoon of oil. Fry the tomatoes all around for about 5 minutes. Season with coarse salt and pepper.
Remove the chicken fillets from the oven, cut into slices and arrange on plates with mashed potatoes and tomatoes. Garnish with chervil.