[STEP 1]
In a large bowl, stir spinach, ricotta cheese, 2 cups mozzarella cheese, Parmesan, garlic and Italian seasoning.
[STEP 2]
Divide and fill each shell with ricotta mixture.
[STEP 3]
Add 3 cups sauce to the bottom of the crock.
[STEP 4]
Place 14 stuffed shells in the bottom of the crock. Spoon 2 cups marinara sauce over shells.
[STEP 5]
Top with remaining stuffed shells and sauce.
[STEP 6]
Cover slow cooker and cook on HIGH for 3 to 4 hours or LOW for 6 to 8 until shells are cooked. Remove lid and sprinkle remaining mozzarella cheese over shells. Wait 5 minutes until cheese is melted. Garnish with parsley.