Preheat broiler.

Place a large pot of salted water over high heat and bring it up to a boil. Cook the pasta to al dente according to package directions. Drain and reserve in the pot it was cooked in.

While the pasta is cooking, place a large skillet over medium-high heat with 2 tablespoons EVOO, about 2 turns of the pan. Add the ground meat to the pan and cook, breaking it up with a wooden spoon, until evenly browned throughout, about 6-7 minutes.

Add the onion and garlic to the pan and continue cooking until the onion has softened, 6-7 minutes. Add the spinach and cook about 1 minute to heat through, then season the mixture with salt and freshly ground black pepper.

While the onions are cooking, place a medium-size pot over medium heat and melt the butter. Sprinkle the flour over the butter and cook the mixture for about 1 minute. Whisk the milk into the butter-flour mixture and cook until the liquid has thickened up. Season the sauce with nutmeg, salt and freshly ground black pepper.

Add the meat-onion mixture and the sauce to the pot with the cooked pasta and stir to evenly combine. Transfer the mixture to a casserole dish and sprinkle the grated cheese over the top. Place the dish under the broiler until the cheese is melted and golden brown.