Preheat your Oven to 375°F. Generously spray a standard 12 cups Muffin Tin with Cooking Spray and set aside.

In a small Mixing Bowl, whisk together the ⅓ cup ketchup, 2 tbsp brown sugar packed, and 1 tbsp yellow mustard until smooth. Set aside.

In a large Mixing Bowl, combine the 1 ½ lb ground beef 80/20 lean-to-fat ratio recommended, beaten 1 large egg lightly beaten, diced ½ cup yellow onion finely diced, ½ cup whole milk, ¾ cup dried breadcrumbs plain or Italian-seasoned, 1 tsp garlic powder, 1 tsp salt, ½ tsp black pepper freshly ground, and 1 tsp Worcestershire sauce. Mix with your hands or a Dipping Fork just until everything is evenly incorporated — do not overmix, or the meatloaves will be dense.

Divide the meat mixture evenly among the 12 Muffin Tin cups, pressing gently to fill each one. Spoon a generous teaspoon of the ⅓ cup ketchup glaze over the top of each mini meatloaf and spread to cover.

Pull the brisket from the Refrigerator 30 to 60 minutes before cooking to let it approach room temperature. Trim hard fat down to about a quarter inch. Apply your dry rub or salt-and-pepper blend evenly over the whole surface, pressing it in firmly. Soak Wood Chips in water for at least 30 minutes if your Smoker uses chips, or prep wood chunks and pellets per your smoker's directions. Empty the drip tray before you start. Set aside unwaxed Butcher Paper or heavy-duty Aluminum Foil for wrapping later in the cook.

Preheat your Smoker to 225–250°F and verify the temperature with a standalone Meat Thermometer. Add Wood Chips, chunks, or pellets per your smoker's instructions. Place the brisket fat side up with the point end toward the heat source. Close the smoker and avoid opening it often. Check wood and adjust vents every 45 minutes to hold 225–250°F. Rotate the brisket every 3 hours and flip if one side colors faster. Smoke uncovered until the internal temperature hits 165°F and a dark bark has formed, about 5 to 8 hours. Wrap tightly in Butcher Paper or Aluminum Foil, return to the smoker, and continue until an Instant-Read Thermometer reads 195–203°F and the meat is very tender but not falling apart, roughly 4 to 5 more hours. Total cook time is typically 8 to 12 hours. Use internal temperature and texture as your doneness cues, not the clock alone.