Cook the Sausage and Onions: Start by adding the ground Italian sausage to a large skillet over medium heat. Let it cook for a couple of minutes until it begins to brown, then add in the diced onions, stirring occasionally until they become translucent and fragrant.
Prepare the Sauce Mixture: Once the sausage is browned and onions are softened, add your crushed tomatoes, water, Italian seasoning, sugar, garlic powder, and salt into the skillet. Stir everything together well and bring this mixture to a boil.
Add Noodles: Break the uncooked lasagna noodles into roughly 1-inch pieces and gently stir them into your bubbling sauce mixture. Cover your skillet with a lid and let it boil while stirring frequently to ensure even cooking for about 18-20 minutes or until your pasta is tender.
Incorporate the Cheeses: After boiling, remove your skillet from heat and add dollops of ricotta cheese on top of your cooked pasta mixture. Sprinkle shredded mozzarella cheese generously over everything before covering with a lid again, allowing it to sit for a few minutes until melted.
Final Touches and Serve: Once your cheese has melted beautifully, uncover your Skillet Lasagna and sprinkle with grated parmesan cheese if desired along with chopped parsley for added freshness. Serve warm as a comforting main course that everyone will love!