In a large mixing bowl, combine the ground turkey, Worcestershire sauce, salt, black pepper, and garlic powder. Use your hands to thoroughly mix everything together until well combined. Then, divide the mixture into 6 equal portions (about 1/3 lb each) and form each portion into a patty. Cover the patties with plastic wrap and place them in the refrigerator to chill while you prepare the other ingredients.

Preheat a griddle or grill over medium-high heat (around 400°F). Brush the cut sides of the hamburger buns with melted butter. Place the buns buttered-side down onto the griddle and toast for about 2 minutes until golden brown. Set the toasted buns aside. I find that toasting the buns really makes a difference in both texture and flavor!

Spread the oil over the preheated grill or griddle, using a spatula to coat the cooking surface. Remove the chilled turkey patties from the refrigerator and place them on the grill. Top each patty with a piece of parchment paper, then firmly press down with a burger press or large spatula to smash them into thin patties. Discard the parchment paper. Cook the patties for 2-3 minutes, until juices start appearing on the surface and the color begins to change. Carefully scrape under each patty to lift and flip them, making sure to keep the caramelized crust intact. After flipping, do not press down again.

Continue cooking the flipped patties for 1-2 more minutes, or until they reach an internal temperature of 165°F. Place a slice of American cheese on top of each patty and let it melt over the hot patties before removing them from the grill.

To assemble each burger, place a leaf of lettuce and a few slices of red onion on the bottom half of each toasted bun. Top with a cheese-topped turkey patty (from Step 4), then add sliced tomato, and finally the top half of the bun. Serve immediately while the patties are still warm and juicy. For something extra, I sometimes add a little mayo or burger sauce to the buns before assembling!