Preparation

• Preheat your oven to 425 degrees F (220 degrees C). Grease a 12×17-inch baking sheet with 1 to 2 tablespoons of olive oil.
• Heat 1 tablespoon of olive oil in a frying pan over medium heat. Add minced garlic and sauté until fragrant, about 30 seconds.
• Add fresh spinach and a pinch of salt. Cook and stir until wilted, about 3 minutes. Transfer spinach to a bowl, chop roughly with kitchen shears, and stir in ricotta cheese. Set aside.
• Wipe out the frying pan and add remaining 2 tablespoons of olive oil. Add spicy sausage and cook undisturbed for 1 to 2 minutes until browned. Break sausage apart and continue cooking until fully browned, about 5 minutes. Add diced red onion and sauté until softened, about 3 minutes. Remove from heat.
• In a large pot, bring salted water to a boil. Add lasagna sheets and cook for about 4 minutes while stirring occasionally. Drain pasta and return to pot, drizzling with olive oil if not mixing immediately.
• Stir marinara sauce into the cooked sausage mixture, then pour this into the pot with the lasagna sheets. Add 1.5 cups of mozzarella and 1 cup of parmesan, mixing until well coated.
• Spread the pasta mixture evenly on the prepared sheet pan or dish. Sprinkle the remaining cheese on top, and dollop the spinach-ricotta mixture across the surface.
• Bake in preheated oven, uncovered, for about 30 minutes, until cheese is golden and the sauce is bubbling. Serve warm.