Cheesy Spinach Lasagna – Lodge Cast Iron

Ingredients

• 4 yellow onions, chopped
• 4 tablespoons olive oil
• 2 tablespoons sugar
• ¼ teaspoon salt
• ¼ teaspoon pepper
• 16 cloves garlic, minced
• 1 teaspoon crushed red pepper
• 8 tablespoons tomato paste
• 4, 28 ounce cans whole tomatoes
• 2.5 tablespoons oregano
• Salt and pepper to taste