Manicotti are very large ridged pasta tubes that are stuffed and baked. The filling is a tasty combination of cheeses, often with the addition of ground meat or vegetables. In this simple weeknight version, the pasta is stuffed with a three-cheese filling flavored with garlic and nutmeg. Ricotta adds creaminess, mozzarella melts and binds, and Parmigiano-Reggiano adds nutty flavor and salinity. For ease and speed, this recipe suggests the use of store-bought marinara sauce. If you’d like to add some greens to the dish, thaw a 10-ounce package of frozen spinach, squeeze out all the water, then finely chop the spinach and add it to the filling before stuffing the manicotti.