1. Preheat the oven to 425 degrees.

2. In large (10 inch or larger) cast iron skillet or other oven safe pan (such as a Dutch oven), heat the oil over medium heat. Add the onions and garlic, and cook until softened, about 3-5 minutes. Add the ground beef, break apart and cook until browned, another 5 minutes or so. Drain any excess water/fat.

3. Add the marinara sauce and stir. Break apart the lasagna noodles and add them the pan, covering each piece as fully as possible. Add 1/2 cup water and stir to ensure the lasagna noodle pieces nestled within the meaty tomato sauce as much as possible. For best results, press the mixture down into an even layer.

4. Next, we add a cheese layer. Sprinkle parmesan cheese over the top. Add the ricotta cheese, in dollops, no need to spread it evenly. Finally, cover the entire lasagna with the mozzarella cheese.

5. Transfer the large skillet to the oven and bake for 15 minutes. Allow the whole lasagna pan to rest for 10 minutes before serving individual portions.