01 - If including meat, brown the ground beef or sausage in a skillet over medium heat until fully cooked through. Drain any excess fat and set aside.
02 - Add the cubed processed cheese, cubed cream cheese, the entire can of Rotel diced tomatoes with green chilies (including juices), and the cooked meat (if using) into the slow cooker.
03 - Sprinkle the garlic powder and black pepper evenly over the contents of the slow cooker.
04 - Cover the slow cooker and cook on the low setting for 2 hours, stirring occasionally, until all the cheeses are fully melted and the mixture is smooth and creamy.
05 - Keep the dip warm in the slow cooker on the keep-warm setting. Serve with tortilla chips, crackers, or fresh vegetable sticks for dipping.