Preheat oven to 350 degrees. Stir the cooked ground beef into the marinara sauce. Spread 1/2 cup of the marinara sauce in a thin layer on the bottom an 8 x 8 inch cake pan. Place one lasagna sheet over the sauce. If using a different noodle, make sure the noodles cover the entire bottom of the pan. Spread another 1/2 cup of the marinara sauce over the lasagna sheet. Top the sauce with 3/4 cup of ricotta cheese and 1/2 cup of shredded mozzarella.
Top the cheese with a second lasagna sheet. Spread half of the remaining marinara sauce over the second lasagna sheet. Top with the remaining ricotta cheese and another 1/2 cup of shredded mozzarella. Top the cheese with a third lasagna sheet. Spread the remaining marinara sauce and shredded mozzarella cheese evenly over the third lasagna sheet.
Bake in the preheated oven for 25 minutes or until the cheese is melted. Once baked, remove the lasagna from the oven and allow it to cool at least 5 minutes before slicing into the desired size pieces.
Notes
Nutritional values are based on using my 3 ingredient lasagna noodles and my 2-minute marinara sauce. Values will vary if any substitutes are made