Preheat the oven to 190˚C fan / 210˚c electric / 375˚F.
Grill or fry the bacon for a few minutes until it has cooked lightly. You can also place it in the air fryer on 190˚C /375˚F for 3 mins. It will finish cooking in the oven once it has been added to the pastry, so you don’t want to cook it fully.
Cut the pre-rolled pastry sheet into 6 equal-sized squares. If you want to make smaller turnovers for a party food snack, you can make mini ones by cutting them into 8 or 10 squares.
Place a bacon rasher diagonally on each pastry square.
Sprinkle a generous handful of the grated cheese over each rasher of bacon.
Egg wash the corners of the pastry with a pastry brush and fold two corners into the middle, pressing firmly so they stay in place whilst cooking in the oven.
With the egg wash, brush all over the rest of the exposed pastry. This helps the pastry to have a crispy golden brown finish.
Place the turnovers on a baking tray lined with greaseproof paper, leaving enough space for them to puff out a little, 6 should fit nicely on one tray.
Bake in the oven for 15-20 minutes until the pastry is golden & puffed up and the cheese has melted.