Heat a skillet over medium heat on the stove. Add the ground beef into the skillet to cook. Use a spoon or spatula to break up the meat into crumbles.
Cook the ground beef for about 10 minutes, or until it is all browned and no more pink is visible. Drain any excess grease that may be in the skillet.
Add the onions directly into the skillet and sauté for 2-3 minutes. Sprinkle in all of the seasonings and the Worcestershire sauce. Stir it all until it is fully combined.
Turn the heat down to low and add one cup of the shredded cheese into ground beef mixture. Stir it up until the cheese is melted. Remove the skillet from the heat and set aside.
Heat up a flat griddle over medium to make the quesadillas. Place about one tablespoon of butter directly onto the griddle and let it melt.
Place one tortilla on the griddle, add about 1/2 cup of the shredded cheese, then top it with the cheeseburger mixture, and add another 1/2 cup of shredded cheese. Place another tortilla directly over the top and press down.
Cook the quesadilla for about 1-2 minutes, or until the tortilla starts to turn golden brown, then flip it over and cook the other side for 1-2 minutes.
Once both sides are golden brown and the cheese is melted, remove the quesadilla from the griddle and continue this process until all of the quesadillas are made.
Serve with your favorite condiments!