Cook the beef: Heat a skillet over medium heat. Add the ground beef and cook until browned, breaking it up into small pieces with a spoon. Stir in the taco seasoning and a splash of water, and let it simmer until the beef is fully cooked and the seasoning is well incorporated.

Assemble the quesadillas: On one tortilla, sprinkle half of the cheese, followed by a generous portion of the seasoned beef mixture and some chopped green onions. Top with the remaining cheese and place the second tortilla on top.

Cook the quesadillas: Heat the olive oil in a skillet over medium heat. Place the quesadilla in the skillet and cook for 2-3 minutes on each side until the tortilla is golden brown and the cheese has melted.

Serve and enjoy: Slice the quesadilla into wedges, and serve with a dollop of sour cream and a sprinkle of fresh cilantro.