Preheat oven to 200°
Spread puff pastry sheets over round alfoil pie tins and cut to size
Chop leeks and distribute between pies
Sprinkle over diced bacon and grated cheese
Whisk together eggs, cream and milk and pour over pies (don't overfill)
Cook for 30minutes OR part cook until set and freeze. If freezing, thaw partly (e.g. pull out of freezer before reading for break) and cook for 30min or so until heated through.
