Place a medium pot over medium heat and melt the butter. Sprinkle the flour over the melted butter and cook for about one minute. Slowly whisk the milk into the butter-flour mixture and season with salt, pepper and nutmeg. Let it thicken a couple of minutes then stir in about a cup of the Parmigiano Reggiano cheese. Set the sauce aside. Place a large skillet over medium-high heat. Put olive oil in and toss in the cracked clove of garlic and cook for a minute or two to release its aroma and flavor. Add the spinach and wilt it down. Season the greens with salt and pepper. Break the lasagna sheets into large pieces. Boil them till they are very al dente. Drain and put into skillet with greens. Pour the sauce into the skillet stirring to evenly incorporate everything. Transfer to a baking dish sprayed with Pam. Smooth the top down and sprinkle the remaining 1/2 cup of Parigiano Reggiano over the top of the lasagna. Cover with foil and bake for 30 minutes. Remove the foil and let it finish uncovered for about 15 more minutes to brown the cheese.