In a large skillet, heat the olive oil over medium heat. Add the ground beef, breaking it apart with a spatula, and cook until browned, about 5-7 minutes. Drain any excess fat.

1. Add the chopped onion and minced garlic to the skillet, cooking for another 2-3 minutes until softened. Stir in taco seasoning and water, simmer for 3-4 minutes until the sauce thickens. Adjust seasoning with salt and pepper.
2. Lay a tortilla flat and spread a generous amount of the ground beef mixture evenly over half. Sprinkle shredded cheese over the beef. Fold the tortilla to cover the filling, creating a half-moon shape.
3. Heat a nonstick skillet over medium heat and add a small drizzle of olive oil. Place the folded quesadilla in the skillet, cooking for 2-3 minutes per side, or until golden brown and crispy with melted cheese inside. Repeat with the remaining tortillas.
4. Slice the quesadillas into wedges and serve with your favorite toppings, such as sour cream, guacamole, salsa, or fresh cilantro.