• Add the ground beef, bread crumbs, egg, Worcestershire sauce, milk, garlic powder, onion powder, salt and pepper to a large bowl. Mix by hand until the ingredients are evenly distributed, but stop once the mixture looks even to avoid over mixing.
• Press the meat down in the bowl to form an even disk-like shape. Use a knife to divide the hamburger mixture into 8 – 1/4 pound patties. You can also use a kitchen scale if preferred.
• Line a baking sheet with parchment paper or foil. Using your hands, gather the burger mixture one at a time and press firmly into evenly shaped patties. Be sure to shape them just slightly larger than the buns you plan to use since they will shrink slightly during cooking.
• Place the patties on the baking sheet. Use your thumb or the back of a spoon to press a dent in the centre of each patty so they don't puff up as they cook.
• Freeze patties in a single layer on a baking sheet until frozen solid and then transfer them to a freezer-safe container or bag. They will keep well in the freezer for up to 3 months.

When ready to cook frozen burgers:

• Preheat a gas or charcoal grill to medium-high heat (approximately 350-400 degrees F). Brush with a little oil to prevent sticking. Remove the hamburger patties from the freezer.
• Place the burgers on the oiled grill and spread about 1 1/2 teaspoons mustard on the uncooked side of each patty.
• Grill the frozen patties for about 15-20 minutes, flipping 2-3 times (about every 5 minutes), or until cooked through to an internal temperature of 160°F. If you’re adding cheese slices, add them during the last few minutes.
• Allow the burgers to rest for about 5 minutes. Place the hot patties on hamburgers buns, and top with desired toppings. Serve warm.