Crumble-topped Cream Cheese Gateau

For the pastry base: put the flour, cocoa and salt in a mixing bowl and make a well in the centre. Scatter the butter around the well. Put the egg in the centre of the flour and 1 tablespoon water. Add the sugar and with a knife or your finger tips mix the ingredients, until the mixture resembles coarse breadcrumbs. Knead together to form a smooth dough, adding more water if necessary. Wrap in cling film and chill for 30 minutes.

Preheat the oven to 180°C (160° fan) 350°F gas 4. Grease a 25 cm | 10" springform tin. Roll out the pastry on a lightly floured surface and line the base of the tin.

For the cheesecake filling: beat together the mascarpone and quark until smooth. Whisk the egg yolks with the vanilla, sugar and cornflour until creamy, then stir into the quark mixture. Whisk the egg whites until stiff, then fold into the quark.

For the crumble topping: mix the flour with the cocoa powder, coffee powder and sugar. Rub in the butter until the mixture resembles coarse breadcrumbs.