Instructions:
In a bowl, mix ground beef, minced onion, salt, pepper, garlic powder, and egg. Avoid over-mixing; combine just until integrated. Adjust the seasonings to your liking.
Split the meat mixture into two and shape into rectangles slightly larger than six dinner rolls grouped together (two rows of three rolls, side by side, as in the original packaging).
Arrange the meat rectangles on a cookie sheet. Sprinkle additional minced onion on top if desired. Ensure uniform thickness for even cooking. Bake at 350 degrees for about 12 minutes, checking to prevent over or under cooking.
While the meat cooks, split your sets of six buns to create bottoms and tops.
Spoon about two tablespoons of Thousand Island dressing on each of the bottoms and spread evenly.
Once cooked, blot any excess grease from the meat patties with a paper towel. Place the patties on the dressed bun bottoms. Spread additional dressing on top of both patties.
Lay cheese slices over the meat patties. Return the tray to the oven briefly to melt the cheese, usually about a minute or two.
After the cheese has melted, distribute minced onion, pickles, and lettuce evenly over the patties. Cap with the bun tops.
Use a pastry brush to coat the tops of the buns with melted butter and a sprinkle of sesame seeds.
Slice the burgers into individual servings.
Enjoy your homemade petite Big Mac Cheeseburgers!