Heat the olive oil in a large skillet over medium-high heat.
Add the diced onion, diced red bell pepper, diced zucchini, and sliced mushrooms; cook, stirring occasionally, until the vegetables are tender, about 5–7 minutes.
Stir in the minced garlic, dried basil, dried oregano, and crushed red pepper flakes and cook for 30 seconds until fragrant.
Break the lasagna noodles into large pieces and add them to the skillet, arranging so they lie partly submerged.
Pour the jar of pasta sauce and the can of undrained diced tomatoes over the noodles, pressing down any noodles with a spoon so they are covered; season with kosher salt and black pepper to taste.
Reduce heat to medium, cover the skillet, and simmer for 20 minutes or until the noodles are tender but still slightly firm (al dente).
Remove the lid and gently stir in the ricotta cheese until mostly incorporated.
Arrange the sliced fresh mozzarella over the top, replace the lid, and cook until the cheese melts, about 3–4 minutes.
Remove the lid, sprinkle with grated Parmesan and chopped fresh basil, then serve warm.
If your skillet doesn't have a lid, cover it with a large baking sheet while cooking.