Preheat your oven to 350°F (175°C).
Cook the bacon in a skillet over medium heat until crispy. Remove the bacon, chop it into small pieces, and set aside. Reserve some bacon grease in the skillet.
In the same skillet, add the chopped onion and sauté in the reserved bacon grease until soft, about 3-4 minutes. Remove from heat and let cool slightly.
In a large mixing bowl, combine ground beef, cooked bacon, sautéed onions, breadcrumbs, milk, eggs, Worcestershire sauce, garlic powder, salt, and black pepper. Mix until just combined; do not overmix.
Transfer the meat mixture into a greased baking dish or loaf pan, shaping it into a loaf.
Spread ketchup on top of the meatloaf.
Bake in the preheated oven for 60 minutes or until the internal temperature reaches 160°F (71°C).
If desired, sprinkle shredded cheddar cheese on top of the meatloaf during the last 10 minutes of baking.
Once done, let the meatloaf rest for 10 minutes before slicing.
Serve with mustard, if desired.