Preheat oven or grill to 350°F. Line a baking sheet with parchment paper or foil for easy cleanup.
In a small bowl, combine 1 cup panko bread crumbs and 1 cup milk. Stir to combine.
Melt the 1 tablespoon butter in a large sauté pan over medium-high heat. Cook the diced yellow onion until they are fragrant and slightly brown while stirring occasionally, about 3-5 minutes. Reduce the heat to low and add 2 cloves garlic. Cook for 2-3 additional minutes. Remove the pan from heat and set it aside to cool.
In a large bowl, combine the 2 pounds ground beef, 1 large egg, soaked bread crumbs with the milk, 1 tablespoon Worcestershire sauce, 1 teaspoon dried thyme, 1 teaspoon kosher salt, and the cooked onions and garlic. Use your hands to combine the mixture, but try not to overwork the meat. Shape the mixture into a loaf on the parchment-lined baking sheet. Use a sharp knife to cut a crisscross pattern on top.
Bake uncovered in the preheated oven 40 minutes. While the meatloaf is cooking, combine 1/2 cup ketchup with 1 tablespoon spicy brown mustard and 1 tablespoon brown sugar in a bowl. Set aside.
After 40 minutes of cooking, spread the sauce mixture over the top of the meatloaf and continue baking for about 30-35 minutes to an internal temperature of 160°F (70°C).
Video
Notes
Cooking tips for perfect results:
Don't overwork the meatloaf while mixing. Mix it just until everything is combined.
Since it was rec
If you prefer the crunchy outer layer, consider making the meatloaf flat so that you have more surface area to get crispy. This will also reduce your cooking time.
Always use a trusted meat thermometer to verify that the meatloaf is done.