To make the meatballs, crack the eggs into a large mixing bowl and whisk them lightly. Add the chicken, bread crumbs, Parmesan, onion, garlic, parsley, basil, salt and pepper, and using your hands, mix and knead the mixture to combine it well.
Form the mixture into twenty-eight meatballs about 1½- inches in diameter. The mixture will be a bit sticky, so wet your hands as needed to make rolling the meatballs easier. Place the meatballs on a foil-lined baking sheet, and cover them with another sheet of foil. Refrigerate for at least 1 hour or more. The meatballs can be prepared in advance and refrigerated for up to 24 hours.
To make the sauce, add the tomatoes, marinara, water, onion, garlic, Italian seasoning, red pepper flakes, salt and pepper to the slow cooker. Cover and cook for 1 hour on HIGH.
When the sauce is done, place the refrigerated meatballs into the sauce, reshaping them into nice balls as you add them. Spoon the sauce over any exposed meatballs so that they are all immersed in sauce. Cover and cook for 4 to 6 hours on LOW, until the meatballs are thoroughly cooked. Avoid stirring the meatballs during cooking to help them keep their shape.
Once meatballs are cooked through, stir in the cream and basil. Cover and continue to cook for 5 minutes.