Add the ground beef and diced onion to a large skillet over medium heat. Cook until the beef is browned and the onion has softened. Drain excess grease if necessary.

Add the minced garlic and cook briefly until fragrant.

Season with Italian seasoning, beef bouillon powder, dried basil, cayenne pepper, black pepper, and salt to taste.

Stir in the marinara sauce and simmer over low heat for approximately 15–20 minutes. Stir in the fresh parsley and set aside.

In a bowl, combine the ricotta, Parmesan, parsley, garlic powder, Cajun seasoning if using, salt, and pepper. Taste and adjust the seasonings, then mix in the egg.

Spread a thin layer of meat sauce over the bottom of a 9x13-inch casserole dish.

Add a layer of oven-ready noodles followed by meat sauce and mozzarella.

Continue layering, adding the ricotta mixture through the middle layer, until the ingredients are used.

Finish with the remaining meat sauce and mozzarella.

Cover the casserole dish tightly with foil and bake at 375°F for 50 minutes.

Remove the foil and continue baking for another 10–15 minutes, until the cheese is melted, bubbly, and lightly golden.

Remove from the oven and let the lasagna rest for 15 minutes before slicing and serving.