Brown the beef: Heat a large, deep skillet over medium-high. Add the ground beef and cook, breaking it up, until browned and no longer pink, 5–7 minutes. Drain excess fat if needed, leaving about 1 tablespoon in the pan.
Soften aromatics: Add the onion and a drizzle of olive oil if the pan looks dry.
Cook until translucent, about 3 minutes. Stir in the garlic and cook 30 seconds until fragrant.
Build the sauce: Stir in tomato paste and cook 1 minute. Add crushed tomatoes, 1/2 cup water or broth, Italian seasoning, oregano, red pepper flakes (if using), salt, and black pepper.
Bring to a gentle simmer.
Add the noodles: Nestle the broken lasagna noodles into the sauce, making sure they’re mostly submerged. Add a splash more water if needed so the pasta can cook.
Simmer and stir: Reduce heat to medium-low, cover, and cook 12–15 minutes, stirring every few minutes to prevent sticking. Add a little water if the sauce gets too thick before the pasta is tender.
Check doneness: When the noodles are al dente and the sauce has thickened, taste and adjust salt and pepper.
The mixture should be saucy but not soupy.
Add cheese: Dollop ricotta over the top in spoonfuls. Sprinkle evenly with mozzarella and Parmesan. Cover for 2–3 minutes, or until the cheese is melted and gooey.
Finish and serve: Turn off heat.
Let it rest 3–5 minutes so it sets slightly. Top with chopped basil or parsley. Serve straight from the skillet.