Preheat oven to 375 degrees. Cook pasta according
to package. Drain, set aside. In LARGE skillet,
saute onions in olive oil until translucent, about
5 min. Add crumbled sausage, salt/pepper, and
brown well until cooked through. Add 3 1/2 cup
marinara sauce to the sausage mixture, bring to a
boil. Remove from heat.
Spray 13x9 in baking dish w/ cooking spray. Pour 1
cup marinara sauce on the bottom. Layer 5 sheets
of lasagna, top w/ 1 cup of sausage mixture, 1/2
cup ricotta and 2 TBS of Parmigiano-Reggiano
cheese. Repeat for 2 more layers. On the top layer
pour the remaining sauce and Parmigiano cheese.
Add mozzarella and cover with foil. Bake 25 min,
uncover and bake extra 5 min. Let rest 15 min