01 -
Place the bacon in a large skillet over medium heat. Cook for 7-9 minutes, turning as needed, until crisp. Transfer to paper towels, cool slightly, and chop into small pieces.
02 -
In a bowl, stir together the chilled mac and cheese, chopped bacon, ranch dressing, cheddar, mozzarella, green onions, and black pepper. The mixture should be thick and scoopable.
03 -
Lay the tortillas on a work surface. Divide the filling over one half of each tortilla, leaving a 1/2-inch border. Fold the empty half over the filling and press gently.
04 -
Wipe out the skillet and return it to medium heat. Melt 1/2 tablespoon butter, add one quesadilla, and cook for 3-4 minutes until the bottom is golden and crisp.
05 -
Flip carefully with a wide spatula. Cook for another 3-4 minutes until the second side is golden and the center is hot and melty. Repeat with the remaining quesadillas and butter.
06 -
Let each quesadilla rest for 1 minute before slicing into wedges. Serve hot with extra ranch or hot sauce if you like.