Plug in the slow cooker and begin preheating on low
Mix the garlic powder, salt, and pepper together and set aside
Crumble the ground beef into a mixing bowl
Sprinkle the chopped onion and Worcestershire sauce over the meat and lightly mix together
Sprinkle with the seasoning mixture and lightly mix again
Add the egg and bread crumbs or cracker crumbs
Mix just until combined, being careful not to overmix
Shape the mixture into a loaf
Fold a sheet of foil into a sling and place it in the bottom of the slow cooker
Place the meatloaf on the foil sling
Mix the brown sugar and ketchup together
Reserve 1-2 tbsp glaze for broiling, if desired
Brush the remaining glaze over the meatloaf
Cover and cook on high for 4 hours, or until the meatloaf reaches an internal temperature of 160°F
The meatloaf is ready to serve at this point
For a more caramelized glaze, carefully lift the meatloaf from the slow cooker using the foil sling and place it on a baking sheet
Brush with the reserved glaze
Broil briefly, watching carefully, until the glaze is caramelized