Add the ground sausage to a large skillet over medium-high heat. Cook for six to eight minutes, breaking the sausage into small crumbles as it cooks. Continue cooking until no pink remains and the meat reaches 160°F.
Drain the excess grease from the cooked sausage.
Lightly spray a 4 to 5-quart slow cooker with nonstick cooking spray.
Add the cubed Velveeta, cream cheese, undrained tomatoes with green chilies, sour cream, milk, garlic powder, onion powder, smoked paprika, and black pepper to the slow cooker.
Add the cooked sausage.
Cover and cook on low for one to two hours. Stir after one hour, then continue cooking until the cheese has melted completely.
Stir until the dip is smooth and the sausage is evenly distributed. Add additional milk one tablespoon at a time if you want a thinner consistency.
Stir in the sliced green onions.
Switch the slow cooker to warm. Garnish with additional green onions if desired and serve with tortilla chips, corn chips, crackers, or fresh vegetables.