Heat the oil in a large frying pan over a medium-high heat.
1/2 tbsp oil
Add the bacon and fry for 5 minutes, until lightly browned.
4 strips streaky bacon
Turn the heat down to medium. Add the onion and pepper and cook, stirring often for a further 5 minutes, until the onion softens.
1 small onion, 1/4 tsp black pepper
Sprinkle over the flour and cook for a further minute, stirring constantly.
1 tbsp plain (all purpose) flour
Slowly pour in the milk while stirring, until all of the milk is incorporated.
240 ml (1 cup) milk (full-fat or half-fat)
Continue to slowly stir, whilst heating until the sauce thickens, then stir in the cheese and cooked chicken.
50 g (1/2 packed cup) strong cheddar cheese, grated/shredded, 200 g (7 oz) cooked shredded chicken
Turn off the heat and leave to cool for 10 mins.
Preheat the oven to 200C/400F (fan) and line a baking tray with parchment or a silicon liner.
Unroll the pastry sheet and slice into 8 equal rectangles.
1 roll puff pastry
Place four of the rectangles on the prepared baking sheet, leaving a good gap around them.
Spoon quarter of the cheese-bacon mixture into the centre of each rectangle, then brush egg wash around the edges of the pastry.
1 small egg
Top each with another pastry rectangle and seal the edges together with a fork.
Score the pasties a few times with a sharp knife (don't go all the way through), then brush the top of each of the pasties with egg wash.
Create a couple of small holes in the centre of each, using the tip of the knife (to allow steam to escape).
Place in the oven for 20 minutes, until golden brown then serve.
Video
Notes
Can I make them ahead?
Yes, make and cook the pasties, then cool, cover and refrigerate.Reheat in the oven, uncovered, at 190C/375F for 20 minutes, until piping hot throughout.
Can I freeze them?
Yes, make and cook the pasties, then cool, place in an airtight container (or a layer of greaseproof paper, followed by a layer of foil) and freeze.Defrost in the refrigerator overnight. Reheat as per the 'make ahead' instructions above.
Nutritional information is approximate, per pasty.