Stuffed chicken fillet with mozzarella and spinach

Using a sharp knife, separate the chicken fillets. Make a deep incision in the middle of each to form a pocket for the filling. Braise the spinach in 10 ml heated olive oil for 2-3 min and season it with salt and black pepper. Fill the fillets with the spinach and the mozzarella, cut into thin slices. Season them with salt and black pepper and sear them in a pan with heated olive oil for about 2-3 min on each side. Then finish them in the oven for about ten minutes in an oven preheated to 220°C. After removing them, return them again to the stove, where you melt 20 g butter, add the rosemary and baste the fillets with the fat so they become juicier and more aromatic. Bring the wine to a boil and add the grated emmental and gorgonzola. After they melt, add 20 g butter, pour in the cream and season with salt and black pepper. Let the sauce thicken slightly and remove it from the stove, then blend it with a mixer so it acquires a fluffy and smooth texture. Boil the potatoes until done, drain the water, add the butter and fresh milk and mash them. Season the resulting purée with salt. Serve the stuffed fillet over a bed of mashed potatoes and pour over the sauce.