Step 1: Heat olive oil in a large, deep skillet or Dutch oven over medium-high heat. Add ground meat and cook, breaking it up with a spoon, until browned. Drain any excess fat.
Step 2: Add chopped onion to the pan and cook until softened, about 5 minutes. Stir in minced garlic and cook for another minute until fragrant.
Step 3: Pour in crushed tomatoes, water or broth, Italian seasoning, salt, and pepper. Bring the mixture to a gentle simmer, stirring well to combine all ingredients.
Step 4: Break the oven-ready lasagna noodles into smaller, manageable pieces (about 2-3 inches long). Submerge the noodle pieces into the simmering sauce, ensuring they are mostly covered by the liquid. Stir gently to prevent sticking.
Step 5: Reduce heat to medium-low, cover the pan, and simmer for 15-20 minutes, or until the noodles are al dente and most of the liquid has been absorbed. Stir occasionally to ensure even cooking.
Step 6: While the noodles are cooking, prepare the ricotta mixture. In a medium bowl, combine ricotta cheese, the whisked egg, 1/2 cup of the shredded mozzarella, and optional nutmeg, salt, and pepper. Mix well.
Step 7: Once the noodles are tender, dollop spoonfuls of the ricotta mixture over the top of the lasagna. Sprinkle the remaining 1 1/2 cups of shredded mozzarella and the grated Parmesan cheese evenly over everything.
Step 8: Cover the pan again and cook for another 5-10 minutes, or until the cheeses are melted and bubbly. For a golden-brown top, you can carefully place the oven-safe pan under a broiler for 1-2 minutes (watch closely to prevent burning).
Step 9: Remove from heat and let the One-Pan Stovetop Lazy Lasagna rest for 5-10 minutes before serving. Garnish with fresh basil or parsley if desired. Serve warm and enjoy your effortless lasagna!