Bring a large pot of water to boil for the pasta. Place a rack in the upper third of the oven and preheat the broiler.
In a skillet, heat 1 tablespoon of olive oil, over medium. Melt 1 tablespoon of butter into the oil and when it foams, add 1 small finely chopped onion and 3 cloves of minced garlic. Season with salt and pepper and cook, stirring, 3 to 5 minutes to soften. Stir in 2 tablespoons of flour and cook another minute. Whisk in 2 cups milk and cook until thickened, 5 to 7 minutes. Season with a pinch of nutmeg and reduce heat to low.
Salt the boiling water and cook the pasta to al dente. Reserve 1/4 cup of the cooking water and add to the sauce to thin a bit. Add 1 bag of fresh spinach to the sauce and stir to mix thoroughly. Add the noodles and arrange in a casserole dish. Dot 1 1/2 cups of ricotta. Top with 8 ounces of shredded mozzarella and 1 cup of pecorino-romano (or parmesan) cheese and broil until browned, 6 to 8 minutes.
It was quite tasty. The cream sauce really made for a filling meal. Theodore ate the meal but he was not crazy about all the cheese. Still an easy and tasty meal…