I prefer to make my own burgers ahead of time when beef (or sometimes ground turkey!) is on sale and freeze them until needed.
Here’s a simple trick for making the exact same size patty every time so they cook evenly.
Unscrew the lid from a peanut butter jar, line it with a piece of saran wrap (common sense says to wash the lid first), the press the burger down into the lid, forming a perfect patty. Flip over onto wax paper and repeat until you have as many premade burgers as you need!
You can choose to season the burger meat first or after, or when you cook it, you could mix in finely diced onions or minced garlic or herbs, etc.
This also works for crab cakes, clam cakes, homemade veggie burgers, etc.