Preheat the oven to 375°F (190°C).
Heat a large high-sided skillet or Dutch oven over medium heat and add the olive oil.
Add the chopped zucchini, finely chopped mushrooms and chopped red pepper; season with salt and pepper and cook about 3 minutes until lightly caramelized.
Add the minced garlic and cook 1 minute more until fragrant.
Stir in the pasta sauce, milk and a pinch of crushed red pepper flakes, then mix in the drained sun-dried tomatoes and rinsed lentils with 1/4 cup water.
Break each no-boil lasagna noodle into 2–3 pieces and stir into the sauce, pushing pieces so most are submerged.
Simmer, stirring occasionally, until the noodles are al dente and the lentils are tender, about 15 minutes; add more water a tablespoon at a time if the mixture becomes too thick.
Stir in the fresh spinach and basil until wilted and evenly distributed.
Remove the skillet from heat and evenly top with sliced mozzarella, shredded provolone and grated Parmesan.
Place the skillet on a baking sheet and bake in the preheated oven 10 minutes, until the cheese is melted and bubbly.
Let the skillet rest 5 minutes, then serve with optional pesto and extra Parmesan.
