A turkey smash burger is a great way to indulge in a burger even if you aren't in the mood for a beef burger. This has less calories but lots of flavor!
In a small bowl, stir together ground turkey with butter, Italian seasoning, kosher salt, black pepper, and garlic powder. Form mixture into four even balls.
On a griddle or in a large skillet over medium-high heat, when skillet is hot, drizzle with oil. Add burger and top with some foil or parchment paper. Press the burger into the griddle for 10 seconds. It helps to have a heavy pan to press the burger flat. Let burger continue to cook for one minute.
Flip burger and cook for another 2 minutes on the second side. Due to the thinness of the burger, that should be enough to cook it through, but given that it's turkey and not beef, cook it a little longer if it looks undercooked. (you can also test it with a meat thermometer to see if it is at least 160˚F.)
Optionally, add a slice of cheese to the burger in the last 30 seconds of cooking.
Make burgers by toasting buns, topping with sauce and some lettuce. Add your smashed turkey burgers, and top with red onions plus any other toppings you'd like. Serve immediately.