- One 16-ounce bag organic, frozen spinach, defrosted
- 1 tablespoon olive oil
- 3 tablespoons butter
- 1 small onion, finely chopped
- 3 cloves garlic, finely chopped
- Salt and pepper
- 2 tablespoons flour
- 2 cups milk
- Nutmeg, to taste
- 1 pound medium shell pasta (about 1-inch shells dry)
- 1 1/2 cups fresh sheep's milk or cow's milk ricotta cheese
- 1 tablespoon lemon zest
- 2 tablespoons fresh thyme, chopped
- 1/2 pound mozzarella, diced or shredded
- 1 cup shredded Pecorino (sheep's milk) or Parmigiano-Reggiano (cow's milk) cheese
Wring spinach dry in a clean dishtowel. Separate with fingers to loosen.
Bring a large pot of water to a boil for the pasta.
Place a rack in the lower third of the oven and preheat broiler.
Heat the olive oil, a turn of the pan, over medium to medium-high heat. Melt butter into oil; when it foams, add the onions and garlic. Season with salt and pepper, and stir 3-5 minutes to soften. Stir in flour 1 minute or so. Whisk in milk and let thicken; season with nutmeg to taste and reduce heat to low to keep warm.
Salt boiling water and cook shells to al dente. Reserve 1/2 cup starchy liquid and add to milk sauce to thin it a bit. Add spinach to pasta pot to heat, stir then drain pasta and spinach and toss with sauce; adjust salt and pepper to taste. Arrange in a casserole dish and dot with ricotta cheese mixed with lemon zest and thyme. Top with mozzarella and grated cheese, and broil until brown and bubbly. Serve immediately.