Combine mozzarella cheese, eggs, cracker crumbs, pecans, onion soup mix, and celery salt in a large bowl. Form mixture into small meatballs.
Heat oil in a deep-fryer or large saucepan. Cook meatballs in batches until browned and crispy, about 5 minutes. Drain on a baking sheet lined paper towels.
Transfer meatballs to a large slow cooker. Cover with cream of mushroom soup. Use the empty can to measure and pour in milk. Cook on Low until flavors combine and soup mixture thickens, 30 minutes to 2 hours.
Substitute any nut meal you like. A food processor or coffee grinder can be used to grind the nuts.
Use any kind of cheese you like.
You can cook meatballs in a 50-50 mix of grape jelly and chili sauce (such as Heinz®), soup mix (such as Lipton®) mixed with water or tomato juice, spaghetti sauce, or any flavor soup you like (but it should be thick).
We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. Amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.