- Tomato Sauce:
- 1 tablespoon olive oil
- 2 teaspoons minced garlic
- 1 1/2 teaspoons red pepper flakes
- 2 tablespoons chopped fresh basil
- 1 tablespoon chopped fresh oregano
- 1 (15 ounce) can tomato sauce
- Spinach Filling:
- 1 (5 ounce) package fresh spinach
- 2 tablespoons water
- 1 (8 ounce) container ricotta cheese
- 1/2 cup grated Parmesan cheese
- Roasted Vegetables:
- 1 eggplant, peeled and cubed
- 1 red bell pepper, seeded and cubed
- 1 orange bell pepper, seeded and cubed
- 2 tablespoons olive oil
- salt and ground black pepper to taste
- Polenta:
- 6 cups water
- salt to taste
- 1 1/2 cups polenta
- cooking spray
- Topping:
- 1 cup shredded mozzarella cheese, divided
- 1/2 cup grated Parmesan cheese, divided
- Heat 1 tablespoon olive oil in a saucepan over medium heat. Add garlic and red pepper flakes; cook and stir until golden, about 1 minute. Stir in basil and oregano; cook until fragrant, about 1 minute. Stir in tomato sauce. Simmer sauce until flavors combine, about 20 minutes.
- Combine spinach and 2 tablespoons water in a large skillet over medium heat. Cover and cook until spinach is wilted, 3 to 5 minutes. Drain and cool until easily handled, about 5 minutes. Gather spinach into a ball and squeeze out excess water. Chop coarsely.
- Combine chopped spinach, ricotta, and ½ cup Parmesan cheese in a bowl.
- Preheat oven to 400 degrees F (200 degrees C). Line 2 baking sheets with parchment paper.
- Divide eggplant, red bell pepper, and orange bell pepper between lined baking sheets. Drizzle with 2 tablespoons olive oil and toss to coat. Season with salt and pepper.
- Roast in the preheated oven, stirring every 10 minutes, until tender and browned in spots, about 30 minutes. Remove from oven.
- Bring 6 cups water to a boil; add salt. Pour in polenta in a steady stream, whisking constantly. Reduce heat to low. Whisk until polenta thickens, about 5 minutes. Cover and cook, stirring vigorously every 10 minutes, until polenta is the consistency of porridge, about 30 minutes.
- Reduce oven temperature to 350 degrees F (175 degrees C). Grease a 9×13-inch baking dish with cooking spray.
- Spread half the polenta evenly in the bottom of the baking dish. Layer half of the spinach mixture, roasted vegetables, and sauce on top. Top with ½ cup mozzarella cheese and ¼ cup Parmesan cheese. Repeat layers with remaining polenta, spinach mixture, roasted vegetables, and sauce. Top with remaining mozzarella cheese and Parmesan cheese.
- Bake in the preheated oven until cheese melts and sauce is bubbly, about 20 minutes. Let cool before cutting so layers hold, at least 20 minutes.