Heat the olive oil in a large skillet over medium-high heat.
Add the diced onion, red bell pepper, zucchini, and sliced mushrooms; cook 5–7 minutes until vegetables are tender.
Stir in the minced garlic, dried basil, dried oregano, and crushed red pepper flakes and cook 30–60 seconds until fragrant.
Break the lasagna noodles into large pieces and add them to the skillet, distributing them evenly over the vegetables.
Pour the jar of pasta sauce and the undrained can of diced tomatoes over the noodles, pressing the noodles down with a spoon so they are mostly submerged; season with salt and black pepper to taste.
Reduce the heat to medium, cover the skillet, and simmer for 20 minutes or until the noodles are al dente, gently pressing or stirring once or twice if needed to keep noodles submerged.
Remove the lid and gently stir in the ricotta cheese until incorporated into the sauce and noodles.
Arrange the sliced fresh mozzarella over the top, replace the lid, and cook 3–4 minutes more until the cheese melts.
Remove the lid, sprinkle with grated Parmesan and chopped fresh basil, then serve warm.
