Cook the Noodles: Begin by filling a large pot with water and bringing it to a boil. Add the 12 lasagna noodles and cook them according to the package directions, usually about 8-10 minutes. Once tender, drain the noodles and set them aside, ensuring they do not stick together.
Make the Meat Sauce: In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add 1 pound of ground beef to the pan and brown it, breaking it apart with a wooden spoon. Once the beef is cooked through, stir in 1/2 teaspoon garlic powder, 1/2 teaspoon dried oregano, and season with salt and pepper to taste. Next, pour in the jar of marinara sauce and allow it to simmer for about 10 minutes, giving it time for the flavors to meld.
Prepare the Cheese Mixture: In a medium bowl, combine 2 cups of ricotta cheese, 1/2 cup of grated Parmesan cheese, and 1 egg. Mix the ingredients until smooth and fully incorporated.
Assemble the Lasagna: Preheat your oven to 375°F (190°C). Spread a layer of the meat sauce on the bottom of a 9x13-inch baking dish, enough to cover the bottom. Lay down 4 lasagna noodles on top of the sauce, followed by half of the ricotta mixture and a layer of meat sauce. Sprinkle 1 cup of shredded mozzarella cheese over the sauce. Repeat these layers again (noodles, ricotta, meat sauce, mozzarella). Finish the assembly with any remaining noodles, topping off with the last of the meat sauce, and a final layer of the mozzarella and Parmesan cheese mixture.
Bake: Cover the baking dish with aluminum foil and bake the lasagna in your preheated oven for 30 minutes. After this time, remove the foil and continue to bake for another 15 minutes, or until the top is bubbly and golden brown.
Serve: Once baked, allow the lasagna to rest for about 10 minutes before slicing. This resting time helps the layers set and makes serving easier. Garnish with freshly chopped parsley for an added touch of flavor and color.