Slow Cooker Lasagna Recipe from Jessica Seinfeld

Ingredients

• 2 28-ounce cans crushed tomatoes
• 4 cloves garlic, finely chopped
• 2 tablespoons dried oregano
• 1/2 teaspoon kosher salt
• 1/4 teaspoon red pepper flakes
• 1/4 teaspoon freshly ground black pepper
• 2 15-ounce containers fresh ricotta
• 2 cups grated mozzarella (8 ounces)
• 1/4 cup grated Parmesan
• 16 lasagna noodles (about 3/4 of a 1-pound box)
• 5 ounces baby spinach (about 6 cups packed)