In a large bowl, combine the milk and bread crumbs, stirring until well combined.
Add the eggs, minced onion, garlic, mustard, BBQ sauce, Worcestershire sauce, seasoning, black pepper, and the ground beef.
Stir with a wooden spoon until well combined.
Line your slow cooker with foil, form your meatloaf mixture into an oval, and place it in the bottom of the slow cooker.
In a small bowl, combine the Dr. Pepper, BBQ sauce, and brown sugar.
Pour half over the meatloaf.
Cover and cook on low for 6 hours or high for 4 hours.
Once cooked through, transfer the meatloaf to a baking sheet, then cover it with the remaining glaze and broil for 2-3 minutes.
Slice and serve!