To create these Slow Cooker Salisbury Steak Meatballs, simply follow these easy steps:

1. Combine Ingredients: In a large bowl, mix together ground beef, breadcrumbs, chopped onion, egg, Worcestershire sauce, garlic powder, onion powder, salt, and pepper until well combined.
2. Form Meatballs: Shape the mixture into meatballs, about 1 to 1.5 inches in diameter.
3. Prepare Slow Cooker: Lightly spray the slow cooker insert with cooking spray to prevent sticking.
4. Add Meatballs: Place the formed meatballs into the slow cooker in a single layer or stacked.
5. Mix Gravy: In a separate bowl, mix together beef broth and onion soup mix until well blended. Pour this mixture over the meatballs in the slow cooker.
6. Cook: Cover the slow cooker and set it to cook on low for 6-8 hours or on high for 3-4 hours.
7. Thicken Gravy (Optional): If desired, mix the cornstarch with water in a small bowl. About 30 minutes before serving, stir this mixture into the gravy to thicken.
8. Serve: Once cooked, serve the meatballs with the gravy over your choice of sides like mashed potatoes or rice.

These straightforward instructions make it easy to whip up a scrumptious meal without fuss.