Preheat ovento 350° Fahrenheit.
In a large bowl, mix the ground beef, 1/2 c. dry breadcrumbs, onion, garlic, milk, Worcestershire sauce, mustard, and spices. Mix well with your hands.
Add the egg and mix, until it is fully incorporated into the meat mixture.
Then, add the bread cubes and mix thoroughly with your hands once again. If the mixture is too wet, sprinkle in additional dry breadcrumbs a 1/2 c. at a time, until the meatloaf reaches a consistency where it is not too dry/wet and sticks together easily.
Add the meat mixture to a loaf pan or cake pan. Shape the meatloaf into your desired shape, such as: a giant hand, foot, or pumpkin (as seen in the photos included in this post); or any other ghoulish shape your haunted heart desires.
Use the largely diced onions as "fingernails" and/or "toenails" on the monster's hand or foot, respectively.
Gently pat the meat down into an even layer and cover with foil. Bake in oven for 20 minutes.
While your monstrous meatloaf is baking, mix the remaining ketchup, brown sugar, soy sauce, and vinegar in a small saucepan. Heat on low, stirring constantly, for5-10 minutes, until the sauce is fully incorporated and begins to thicken. Remove from heat.
After 20 minutes of baking, pull meatloaf from oven and remove foil. Top with sauce.
Return the Monster Mash Meatloaf to the oven and continue baking for an additional 30 minutes, uncovered.
Let the meatloaf rest for approximately 8-10 minutes before slicing and serving.(Otherwise, it may fall apart.)