Wash and drain the spinach. Peel and slice the garlic. Heat 1 tablespoon of oil in a large frying pan. Add garlic and 50 ml broth. Steam the spinach for 2-3 minutes, turning until the spinach has completely collapsed.
Season to taste with salt, pepper, nutmeg and sugar, remove and drain. Peel and chop the onion. Heat 1 tablespoon of oil in a large pot. Fry the onion until transparent. Deglaze with pizza sauce and 150 ml broth and simmer covered for 1-2 minutes.
Wash basil, dab dry, pluck leaves from the stalks and chop. Add the ravioli, basil and spinach to the sauce. Dice half the mozzarella, cut the other half into slices. Stir the mozzarella cubes into the ravioli.
Fill the ravioli with spinach, cheese and sauce into a casserole dish and cover with slices of mozzarella. Bake in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for approx. 10 minutes until brown.