Spray the crockpot with cooking spray or line with a crockpot liner.
Pour about half of the pasta sauce into the base of the crockpot.2 24-ounce jars of pasta sauce
In a large bowl, combine 1 32-ounce container ricotta cheese, 1 cup grated mozzarella cheese, ¾ cup grated Parmesan cheese, 2 eggs, lightly beaten, 3 cloves garlic, minced, 1 teaspoon Italian seasoning, ½ teaspoon salt, and ½ teaspoon ground black pepper.
Pipe or spoon the cheese mixture into the shells and place a layer in the crockpot.
Top with some of the pasta sauce, then some of the remaining mozzarella cheese. Repeat layering the filled shells, then pasta sauce, then mozzarella cheese.
Cover and cook on high for 2-3 hours or low for 4-5 hours.
Garnish with parsley and additional Parmesan cheese, if desired.