Heat the oil and brown the garlic. Add the thawed spinach and sauté for 3 minutes, stirring until smooth.
Season with salt, pepper and nutmeg. Remove from heat and add ricotta, cream and milk. Mix well and set aside.
Assembly: in a refractory, assemble layers of tomato sauce, pasta, spinach and grated mozzarella (finish with sauce).
Sprinkle with Parmesan and cover with aluminum foil. Bake in preheated oven at medium temperature for 30 minutes or until hot and bubbly. Serve.
Tip: The lasagna can be assembled and kept in the fridge overnight before reheating. If you prefer, you can freeze it for three months, wrapped in plastic wrap.
No need to defrost to serve. Take it straight to the oven, without the plastic wrap, covered with aluminum foil and bake for 50 minutes or until golden.
Sprinkle with grated cheese and serve.