The sheet of puff pastry should be about 9 inches (23 cm) square for this recipe. If your sheets are a different size, or the pastry comes in a block, roll or trim it into a 9-inch (23 cm) square as necessary. Air fryers become very hot, especially when heated to maximum temperature. Use oven pads or mitts when touching the appliance and when opening and closing the basket. To make adding the egg easier, crack the egg into a small cup before sliding it onto the puff pastry.