Baked Polenta Lasagna with Spinach and Mushroom Ragù

By AislePrompt Test Kitchen · Reviewed by AislePrompt Editorial · Published 2026-05-12 · Updated 2026-05-12

Layers of creamy baked polenta alternate with a savory mushroom and spinach ragù, topped with melted mozzarella for a comforting vegetarian Italian dish. This italian-inspired vegetarian (vegetarian) ready in about 65 minutes pairs instant polenta, water, salt for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 370 calories and feeds 6, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Ingredients

• 1 cup instant polenta
• 4 cups water
• 1 tsp salt
• 2 tbsp olive oil
• 12 oz cremini mushrooms, sliced
• 4 cups fresh spinach, chopped
• 1 medium yellow onion, diced
• 3 cloves garlic cloves, minced
• 2 tbsp tomato paste
• 1 tsp dried oregano
• 1 tsp dried basil
• 1/4 tsp crushed red pepper flakes
• 1 1/2 cups mozzarella cheese, shredded
• 1/2 cup Parmesan cheese, grated
• 1/2 tsp black pepper

Instructions

1. Step 1: Bring 4 cups water and 1 tsp salt to a boil in a medium saucepan. Slowly whisk in 1 cup instant polenta. Reduce heat to low and cook, whisking frequently, for 3-4 minutes until thickened and creamy. Remove from heat and stir in 1 tbsp olive oil.
2. Step 2: Preheat oven to 375°F. Lightly oil a 9x9-inch baking dish.
3. Step 3: In a large skillet, heat remaining 1 tbsp olive oil over medium heat. Add 1 medium diced yellow onion and sauté for 4 minutes until translucent.
4. Step 4: Add 3 minced garlic cloves and 12 oz sliced cremini mushrooms to the skillet. Cook for 6-8 minutes until mushrooms release their moisture and start to brown.
5. Step 5: Stir in 4 cups chopped fresh spinach, 2 tbsp tomato paste, 1 tsp dried oregano, 1 tsp dried basil, 1/4 tsp crushed red pepper flakes, and 1/2 tsp black pepper. Cook for 3 minutes until the spinach wilts and mixture is well combined.
6. Step 6: Spread half of the cooked polenta evenly in the prepared baking dish. Spoon half of the mushroom-spinach ragù over the polenta.
7. Step 7: Repeat layering with remaining polenta and ragù. Sprinkle 1 1/2 cups shredded mozzarella and 1/2 cup grated Parmesan evenly over the top.
8. Step 8: Bake uncovered for 25-30 minutes until cheese is melted, bubbly, and golden on top. Let rest for 10 minutes before slicing and serving.