Place 1 teaspoon kosher salt, 1 teaspoon seasoned salt, 1 teaspoon black pepper, and 1/2 teaspoon garlic powder in a small bowl and stir to combine.
Divide 1 pound ground beef into 4 portions and form into rough, loose balls (do not press them together). Place on a baking sheet or large plate and sprinkle all over with the seasoning mixture.
Heat a 10-inch or larger cast iron skillet over medium-high heat until very hot, about 3 minutes. Add 1 tablespoon canola oil. Working in 2 batches if needed so as not to crowd the pan, add the beef balls. Flatten the balls with a flat spatula to form rough 4-inch wide patties that are about 1/2-inch thick.
Cook until the edges are brown and the beef no longer sticks to the skillet, 2 to 3 minutes. Flip and place 1 slice sharp cheddar cheese on top of each patty, if using. Continue cooking until the cheese is fully melted and burgers no longer stick to the pan, 2 to 3 minutes.
Serve immediately on toasted buns with desired toppings.