Cook the noodles: Boil lasagna sheets in well-salted water until just shy of al dente (about 1 minute less than package directions). Drain and lay them flat on a lightly oiled sheet pan or clean towels so they don’t stick.

Sauté the veggies: In a large skillet, heat olive oil over medium. Add onion, zucchini, bell pepper, and mushrooms with a pinch of salt. Cook 6–8 minutes until soft and the mushrooms release their moisture. Stir in garlic, Italian seasoning, and red pepper flakes; cook 1 minute more.

Wilt the greens: Add spinach to the skillet and cook until just wilted. If using frozen spinach, stir it in until warmed. Transfer the mixture to a bowl and let it cool for a few minutes so it doesn’t melt the cheese.

Mix the filling: In a large bowl, combine ricotta, 1 cup mozzarella, Parmesan, egg, half the chopped herbs, and the cooled veggies. Season with salt and black pepper. The mixture should be thick and spreadable.

Prep the baking dish: Spread 1 to 1 1/2 cups of marinara on the bottom of a 9x13-inch baking dish to create a saucy base.

Assemble the rolls: Lay a noodle flat. Spread 2–3 tablespoons of filling along its length in an even layer. Roll from one short end to the other. Place seam-side down in the sauced baking dish. Repeat with remaining noodles and filling.

Sauce and cheese: Spoon remaining marinara over the tops and sides of the rolls so they’re well coated but not drowning. Sprinkle the remaining mozzarella on top.

Bake: Cover the dish with foil (tent it slightly so it doesn’t stick to the cheese). Bake at 375°F (190°C) for 20 minutes. Uncover and bake 8–10 minutes more, until the cheese is melted and bubbling and the rolls are heated through.

Finish and serve: Let rest 5 minutes. Sprinkle with the remaining fresh herbs. Serve two rolls per person with a side salad or roasted vegetables.