In a medium bowl, combine ground beef, salt, pepper, and garlic powder. Mix well.
Divide ground beef mixture into 4 - ¼ pound balls.
Cook bacon to desired doneness.
Drain bacon grease from skillet and saute onions until caramelized.
Place the ground beef balls on a flat griddle or in a large skillet. They cook quickly so you can use one or two skillets if necessary.
Press the beef until flat and allow to cook 5 - 8 minutes before flipping.
Flip burgers and cook until the desired doneness is reached.
Before removing, add onions, bacon, and Cheddar to each patty. Pour about a tablespoon of water onto the griddle and cover with a dome to melt the cheese. Leave covered for about a minute and check the cheese.
In the meantime, place the buns, cut side down on the grill, and lightly toast. Watch them closely so they don't burn. Remove to a plate.
Once the cheese is melted, remove one patty to the bottom of the bun. Place a second patty on top. Repeat with the other two patties and bun.
Dress the smash burger with condiments you like and serve.