Cut the chicken filets into slices, approx. 1 cm wide. Fry on both sides until golden. Put slices into a fireproof casserole. Deglaze the meat juice with half of the verjuice. Simmer for a little, fill into a bowl, and put aside.
Chop shallots and garlic finely. Sweat them with a little butter until they become translucent. Clean mushrooms and cut into halves or quarters, depending on size. Put into the pan with the onions and garlic, and fry gently. Add mushrooms to the meat. Deglaze onions and garlic with the rest of the verjuice, simmer for a bit, and add to the other half.
Wash basil, pluck and chop leaves. Scatter them over meat and mushrooms.
Mix starch with a little water until smooth. Stir it into the verjuice together with the rest of the water and the cream. Season to taste with salt and pepper. Pour the liquid evenly over meat and mushrooms. Coat with grated cheese.
Cooking time is about 40 minutes at 160 ºC (convection oven) or at 175 ºC (top/bottom heat).
Serve with rice or pasta.