Preheat the oven to 160C/Gas3; line a muffin tray with 12 deep paper cases; stir the melted butter and granulated sugar into the crushed biscuits and divide evenly between the paper cases; press down with the back of a teaspoon; bake for 10 minutes then remove from the oven and leave to cool
For the strawberry puree, put the berries into a food processor with the tablespoon of sugar and blend until smooth; rub through a fine sieve into a bowl and discard the seeds
For the filling, beat the cream cheese, cornflour, sugar and zest together until smooth, then lightly beat in the eggs and crème fraiche; transfer the mixture to a measuring jug so it is easy to pour
Add a little puree to the top of each biscuit base; divide the filling equally between the paper cases, then drop ½ teaspoon of the remaining puree into the centre of the mixture and swirl with a cocktail stick; bake for 25 minutes until puffed up and nearly set, but still slightly wobbly in the centre; they will firm up as they cool; chill for at least 4 hours
Decorate the cheesecakes with the sliced strawberries and mint leaves.