1. Heat the olive oil in a skillet over medium heat, then cook the chopped onion until soft and golden, about 8 to 10 minutes. Let it cool slightly.

2. In a large bowl, combine the ground beef, breadcrumbs, eggs, cooked onion, French onion soup mix, beef broth, Worcestershire sauce, garlic, parsley, salt, and black pepper. Mix gently until just combined.

3. Shape the mixture into a loaf that will fit inside your crockpot.

4. Place a parchment sling or foil strips in the crockpot if you want easier lifting, then set the meatloaf inside.

5. Cover and cook on low for 6 to 7 hours or until the meatloaf is fully cooked and reaches an internal temperature of 160°F.

6. Sprinkle the shredded Gruyère cheese over the top during the last 15 minutes of cooking, then cover again until melted.

7. Carefully lift the meatloaf out, let it rest for 10 minutes, then slice and serve.