Preheat oven to 350 degrees.
Gently crumble beef and sausage into a large bowl.
Add breadcrumbs, beaten egg, milk, onion, garlic, salt, and pepper. Mix together thoroughly with your hands to ensure everything is evenly combined.
Prepare the glaze by mixing ketchup with balsamic vinegar and Worcestershire sauce.
Paint the bottom of your bread pan with two tablespoons of glaze.
Add the meatloaf mixture into the bread pan and press to fill out the pan.
Add all remaining glaze to the top of the meatloaf and place it in the oven.
Bake for 60 minutes, or until it reaches 160 degrees.
Remove from oven, let cool slightly, slice and serve.