Mix beef and condiments: Add cooked beef to a large mixing bowl with ketchup, mustard, and mayonnaise. Mix until beef is well coated and adjust condiments to taste. You'll want the meat to be well-coated, but not too wet.
Cook quesadillas: Heat a large non-stick pan to medium heat and coat with cooking spray. Add your tortilla to the pan. On one half, add a sprinkle of shredded cheese, and 1/4 of the meat mixture, onion, and pickles. Top with additional cheese and fold the tortilla. Cook for 2-3 minutes or until the bottom is golden brown, and flip. Cook the second side for an additional 2-3 minutes or until both sides are golden and crisp. Remove from pan and repeat for all quesadillas.
Serve: Slice your tortillas into triangles and serve immediately. See notes for meal prep instructions.
Calories: 548kcal, Carbohydrates: 31g, Protein: 38g, Fat: 30g, Saturated Fat: 14g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 8g, Trans Fat: 1g, Cholesterol: 116mg, Sodium: 973mg, Potassium: 453mg, Fiber: 4g, Sugar: 4g, Vitamin A: 484IU, Vitamin C: 2mg, Calcium: 436mg, Iron: 4mg