Crock Pot Low Carb Lasagna

Ingredients:

• 1 lb ground beef or ground turkey
• 1 small onion, finely chopped
• 2 cloves garlic, minced
• 1 can (14 oz) crushed tomatoes
• 1 can (14 oz) tomato sauce
• 1 tsp dried basil
• 1 tsp dried oregano
• 1/2 tsp salt
• 1/4 tsp black pepper
• 1/4 tsp red pepper flakes (optional, adjust to taste)
• 2 cups sliced zucchini (about 2 medium zucchinis)
• 1 cup ricotta cheese
• 1 egg
• 2 cups shredded mozzarella cheese
• 1/4 cup grated Parmesan cheese