In a large pan, cook the ground beef over medium heat until it's no longer pink, about 5-7 minutes. Drain any excess fat.
Add the taco seasoning to the cooked beef and stir. Let it cook for 2-3 minutes until the meat is fully coated.
Lay one tortilla flat on a cutting board. Sprinkle some shredded cheese on one half of the tortilla. Add one or two spoonfuls of the cooked beef on top of the cheese. Sprinkle a little more cheese on top of the meat.
Fold the tortilla in half so that the cheese and beef are covered.
Heat a non-stick pan over medium heat and lightly coat with oil. Place the folded quesadilla in the pan and cook for 2-3 minutes on each side until the tortilla is golden brown and the cheese is melted.
Remove the quesadilla from the pan, cut it into wedges, and serve with sour cream, salsa, or other desired toppings. Enjoy!