Step 1: Prepare the breadcrumb mixture - In a large mixing bowl, combine the milk and seasoned bread crumbs. Stir until the crumbs are fully moistened and soft. This step is important because it keeps the meatloaf tender instead of dense.
Step 2: Add the flavor builders - Crack the eggs into the bowl, then add the dried minced onion, minced garlic, mustard, BBQ sauce, Worcestershire sauce, seasoning salt, and black pepper. Stir everything together until well combined.
Step 3: Mix in the ground beef - Add the lean ground beef to the bowl. Using a wooden spoon or clean hands, gently mix until everything is evenly incorporated. Be careful not to overmix, as that can make the meatloaf tough.
Step 4: Shape the meatloaf - Line your slow cooker with foil, leaving enough overhang to lift the meatloaf out later. Shape the meat mixture into an oval loaf and place it gently into the bottom of the slow cooker.
Step 5: Make the glaze - In a small bowl, combine the Dr. Pepper, BBQ sauce, and brown sugar. Stir until the sugar is mostly dissolved and the glaze is smooth.
Step 6: Glaze and cook - Pour half of the glaze over the meatloaf, spreading it evenly across the top. Cover the slow cooker and cook on low for 6 hours or on high for 4 hours, until the meatloaf is cooked through.
Step 7: Optional broil for extra flavor - If you want a sticky, caramelized finish, carefully lift the meatloaf out using the foil and transfer it to a baking sheet. Spoon the remaining glaze over the top and broil for 2 to 3 minutes, keeping a close eye on it.
Step 8: Slice and serve - Let the meatloaf rest for a few minutes before slicing. Serve warm and enjoy every comforting bite.