1 sheet of puff pastry, or 1/2 of a 500 g block, rolled out
3 tbsp half-fat crème fraîche
4 tbsp gruyère, grated (or other cheese of your choice)
8 slices thin streaky smoked bacon
4 eggs plus 1 extra beaten for glazing
Heat the oven to 200C/fan 180C/gas 6. Cut the pastry into 4 squares and lay them on a baking sheet. Score a border 1cm in from the edge of each piece of pastry but don’t go all the way through.
Mix the crème fraîche and cheese, and season. Divide between the tarts and use a fork to spread it out up to the borders.
Run the flat of a knife along the rashers to stretch and flatten them as much as you can, then cut each piece in half so that 4 cut pieces will almost cover each tart.
Glaze the edges of the pastry with beaten egg. Bake the tarts in the oven for 10 minutes, then take out to add the egg. Before adding, gently tip each egg into a fine sieve. This will get rid of the extra-watery bits of white that can make the tarts soggy. Slide each egg out of the sieve onto a tart. Bake for another 8-10 minutes until the white is set. Season the egg before serving.