Break the lasagna noodles into roughly 2-inch pieces and set them aside.
Heat the olive oil in a large, deep skillet over medium heat. Add the onion and cook for 3–4 minutes, until softened. Add the garlic and cook for another 30 seconds.
Add the ground beef, Italian seasoning, and salt. Cook, breaking the meat into small pieces, until browned and cooked through. Drain any excess grease if needed.
Stir in the tomato paste and cook for 1–2 minutes, stirring often.
Pour in the marinara sauce and beef broth and stir until combined. Increase the heat to medium-high and bring the mixture to a gentle boil.
Once it comes to a gentle boil, add the broken lasagna noodles (or noodles of choice) and stir well, making sure the pieces are mostly submerged in the sauce. Reduce the heat to medium so that the sauce maintains a gentle simmer. Cook uncovered for 12–15 minutes, stirring frequently and gently separating any noodles that begin sticking together, until the noodles are al dente. Note: If you're using a different type of smaller pasta shape like mafaldine or bowtie, it will cook through quicker. Use the package directions as a guide.
Check the sauce as the noodles cook. If the sauce becomes too thick before the noodles are tender, add additional splashes of beef broth or water as needed. When the noodles are al dente, there should still be some loose sauce visible between them. The sauce will continue to thicken once the cheese is added and as the pasta rests.
Remove the pan from the heat. Stir in the Parmesan and ½ cup of the mozzarella until melted and combined.
Dollop the ricotta throughout the pasta and gently fold or swirl it in a few times. Try not to completely mix it into the sauce so that you still have creamy pieces of ricotta throughout.
Sprinkle the remaining ½ cup mozzarella evenly over the top. Cover the pan for 2–3 minutes, or until the cheese is melted.