Preheat oven to 350°F and grease 9x13 casserole dish.
Beef:
Preheat a medium cooking pan over medium heat.
Add oil and saute diced onion until transparent.
Add ground beef and cook, breaking up all the lumps, until just done. Season with salt, pepper, and oregano.
Once the meat is just done. Mix in 1 1/2 cups of marinara sauce and 1/3 cup grated Parmesan cheese. Set aside.
Ricotta:
Combine all ingredients for the ricotta layer in a mixing bowl and mix very well. Set aside.
Lasagna:
Spread 1 cup of marinara sauce over the bottom of the casserole dish. Make sure it's spread evenly.
Layer lasagna noodles in one even layer. I like to overlap the pasta sheets just a little bit, 1/2 to 1/4 inch or so.
Spread beef mixture over the pasta sheets evenly. Spread 1 1/2 cups of shredded Italian cheese mix.
Layer lasagna noodles in one even layer. Again, you can overlap the pasta sheets just a little bit, 1/2 to 1/4 inch or so.
Spread 1 cup of marinara sauce over pasta sheets evenly.
Spread ricotta mixture evenly. Drop spoonfuls of ricotta mixture all over and use your hands to spread it in one even layer. (Of course, make sure your hands are clean.)
Layer lasagna noodles in one even layer. Overlap the pasta sheets just a little bit, 1/2 to 1/4 inch or so.
Spread 1 cup of marinara sauce over pasta sheets, evenly.
Spread 1 1/2 cups of shredded Italian cheese mix over the sauce evenly.
Sprinkle some oregano over the top.
Spray one side of aluminum foil sheet with cooking spray and cover the casserole dish with foil, oiled side down. This will help with the cheese sticking to the foil.
Bake covered for about 35 minutes.
Take off the foil and bake for another 10-15 minutes.
Video
Notes
Cheese Options: For the best results, use shredded whole milk mozzarella and fresh grated parmesan. You can also use shredded Italian cheese mix for an even cheesier flavor variety! You can mix in some Asiago with parmesan or Fontina with mozzarella. Both flavorful options.
Leftover ricotta? Use the leftover ricotta in delicious recipes like Ricotta Pancakes, Easy Ricotta Doughnuts, and more! You can even toss it into pound cake batter, add it to a quiche or breakfast egg muffins, make a flatbread for lunch, or use it to stuff French toast.
Storing: store lasagna right in the casserole dish you baked it in. Make sure it’s completely cooled before adding to the refrigerator and cover it tightly with plastic wrap or a lid. It should stay fresh for 3-5 days in the fridge.
Reheat individual portions of lasagna in the microwave, or you can reheat larger portions in the casserole dish in the oven at 325°F covered with aluminum foil. Note that to reheat in the oven it could take up to 20 minutes.