Start by cooking the lasagna noodles in a large pot of boiling water. When the noodles are slightly al dente, strain them and set aside.
In a large pan cook the ground beef and Italian sausage.
When the meat is browned, add the jar of tomato sauce, Italian seasoning, nutmeg, red pepper flakes, and black pepper to the pan.
Cook for 15 minutes.
Set the meat sauce aside to cool.
In a small bowl, stir together the grated Parmesan and ricotta cheese.
Now to assemble the lasagna: pour 1/2 cup of sauce into the bottom of a large 9x13 pan.
Top the sauce with enough lasagna noodles to cover the bottom of the dish.
Layer the noodles with more meat sauce, ricotta cheese mixture, and then lasagna noodles. Repeat these layers until your ingredients are gone, ending with a layer of meat sauce on top.
Cover top of lasagna with mozzarella cheese.
Bake at 375 covered for 45 minutes.
Uncover and bake the lasagna for another 10 minutes.
Let it sit for 15 minutes before serving!