Slow Cooker Ravioli Casserole

Ingredients

• 1 1/2 pounds lean ground beef
• 1 onion, chopped
• 1 clove garlic, minced
• 1 (15-ounce) can tomato sauce
• 1 (14.5-ounce) can stewed tomatoes
• 1 cup water
• 1 teaspoon oregano
• 1 teaspoon Italian seasoning
• salt, to taste
• pepper, to taste
• 10 ounces frozen spinach, thawed
• 1 (16-ounce) box bow tie pasta, cooked
• 1/2 cup parmesan cheese, shredded
• 1 1/2 cups mozzarella cheese, shredded