Heat a large skillet over medium-high heat. Add ground beef and cook, breaking it apart with a wooden spoon, for 5-7 minutes or until browned and no pink remains. Drain excess grease.

Return the skillet to medium heat. Sprinkle taco seasoning over beef and stir to coat. Pour in water or broth and simmer for 2-3 minutes until thickened. Remove from heat.

Place a tortilla on a clean surface. Sprinkle 1/4 cup cheese on one half. Spoon seasoned beef over cheese, then top with another 1/4 cup cheese. Fold tortilla over to form a half-moon.

Heat a skillet over medium heat with a touch of olive oil or butter. Cook quesadilla 2-3 minutes per side or until golden brown and cheese melts. Repeat with remaining tortillas.

Let rest for 1 minute before slicing into wedges. Serve warm with desired toppings like sour cream, guacamole, or salsa.