Place oven rack 4 to 5 inches from heat. Turn oven on to Broil. Prepare sheet pan by lining with foil or spraying lightly with nonstick spray.
In a large bowl, lightly beat egg until combined. Add ground turkey, taco seasoning, and crushed tortilla chips. Finely mince onion or coarsely grate it over the bowl to catch all the juice. Mix everything together using your hands until mixture is combined. Do not overmix.
1 large egg, 1 pound ground turkey, 1 tablespoon taco seasoning, 1 cup finely crushed tortilla chips , ½ small yellow onion
Form into four equal patties, pressing down the middle of each so they are slightly thinner in the middle. Arrange on prepared sheet pan.
Broil about 6 minutes or until golden brown, flip, cook for another 4 to 5 minutes, or until internal temperature measures 165°F. Top burgers with cheese, broil 15 to 30 seconds or until cheese is melted (watch carefully!).
4 slices cheese
Add to buns, top as desired, and serve immediately.