Brûléed cheesecake

Preheat the oven to 200˚C, gas mark 6. Grease a 20cm loose-bottomed, deep cake tin and line the base with baking parchment. Mix the digestives, butter, demerara sugar and ginger until evenly mixed. Use a straight-sided glass to press the crumbs evenly across the base of the tin and 3cm up the sides. Bake on a flat baking sheet for 10 minutes, until golden brown. Brush the egg yolk over the biscuit shell, then bake for 3 minutes more to seal.

Put the lemon zest, soft cheese, sugar, cornflour and vanilla in a large bowl and mix well with a spatula. Work in the eggs until smooth, then fold in the crème fraîche.

Pour the filling over the base. Bake for 10 minutes, then turn the oven to 140˚C, gas mark 1, and bake for 45 minutes more, or until set with a gentle wobble. Leave in the turned-off oven with the door ajar for 1 hour, then loosen the edges with a palette knife and cool completely. Chill well.

Remove the tin; dab away any moisture from the top of the cake. Scatter the sugar over the top. With a kitchen blowtorch, brûlée until the sugar turns deep coppery brown. Serve as soon as you can.