Step 1

Preheat the oven to 180ºC, gas mark 4. lightly grease a 20cm loose-bottom sandwich tin. Put the biscuits in a food processor and whizz to fine crumbs. Add the butter and egg white and whizz again until the crumbs are coated.

Step 2

Spoon the crumbs into the tin and, using the back of a spoon (or with your fingers), press evenly over the base and sides. Set on a baking tray and bake for 10 minutes. Remove from the oven, lightly press the base down with the back of a spoon to level and set aside.

Step 3

Reduce the oven temperature to 150ºC, gas mark 2. In a small bowl, mix the gooseberry preserve with 1 tbsp elderflower cordial; spread over the base.

Step 4

In a separate bowl, gently whisk together the crème fraîche, icing sugar and whole eggs until smooth. Gradually stir in the remaining cordial; carefully pour over the preserve in the tart. Transfer to the oven and bake for 40-45 minutes, until just set, with a wobble in the centre. Remove from the oven and leave to cool, then chill until firm, about 1-2 hours.

Step 5

Meanwhile, make the topping. Put the gooseberries, sugar, lemon juice and 3 tbsp cold water in a saucepan. Gently heat until the sugar has dissolved, then bring to a simmer and bubble until the gooseberries are soft, but still retain some shape, about 3-4 minutes. Slacken the cornflour with 1 tbsp cold water, then add to the gooseberries and bubble for 1 minute. Set aside to cool, then chill until needed.

Step 6

When ready to serve, transfer the tart to a serving plate. Spoon over the gooseberry topping and slice to serve.