Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine your ground beef, breadcrumbs, chopped onion, minced garlic, ketchup, egg, salt, pepper, and milk. Mix well until fully combined.

Shape the mixture into a loaf and place it in a greased loaf pan.

Brush barbecue sauce generously on top of the loaf.

Place your loaf pan in the preheated oven and bake for about 1 hour.

Once cooked through, take it out from the oven and let it rest for about 10 minutes.

Use a sharp knife to cut the meatloaf into thick slices.

Take a slice of your favorite bread, place a slice of meatloaf on top, and then add a slice of cheese.

In a skillet over medium heat, melt a little butter. Add your sandwich, buttered side down, and grill for about 3-5 minutes on each side or until golden brown and crispy.

Slice the grilled sandwich in half and serve hot. You can garnish with extra barbecue sauce if desired.