Cook rigatoni for 5 minutes in a pot of boiling, salted water. Drain and toss with 1 tablespoon olive oil. Set aside.
To make the bechamel sauce:
Melt the butter in a large saucepan over medium heat and add the shallots and garlic. Sweat the shallots and garlic for a few minutes until softened and but not colored. Add the flour and stir until a smooth paste forms. Gradually whisk in the wine and then the milk. Bring the mixture to a simmer, whisking constantly and cook until thickened, about 5 minutes. Season with nutmeg, salt, and pepper, to taste. Let cool slightly.
Transfer cooled bechamel to a large mixing bowl and add the spinach, ricotta, and eggs. Mix in rigatoni and transfer to a greased 9 by13-inch baking dish. Top with grated mozzarella. Cover loosely with aluminum foil and bake for 40 minutes. Remove foil and bake an additional 20 minutes, or until cheese is lightly browned on top, the center is no longer runny, and the sides are bubbly.