- STEP 1
Preheat the oven to 180C/ Gas 4. Lightly butter a 22-24cm springform cake tin, 5-6cm deep, and place on a baking sheet. Crush the biscuits to crumbs in a food processor, transfer to a bowl, add the melted butter and mix until thoroughly combined.
- STEP 2
Tip the biscuit mixture into the cake tin and spread to form a uniform layer, pressing firmly and evenly. Bake for 12 minutes, until firm. Set aside, still on the baking sheet.
- STEP 3
Raise the oven setting to 220C/ Gas 7. Using an electric mixer, beat the cream cheese, milk, sugar, flour and citrus zests together until smooth and lightly creamy.
- STEP 4
On a low speed, incorporate the eggs, one at a time, followed by the yolks. Finally, add the vanilla seeds from the pod. Scrape down the sides of the bowl a few times during mixing, to ensure the filling is homogeneous.
- STEP 5
Pour the filling over the biscuit base in the tin and bake for 12 minutes, then lower the oven setting to 100C/ Gas 1/4 and cook for a further hour until set but still slightly wobbly in the centre. Turn the oven off and leave the cheesecake inside with the door slightly ajar for an hour to cool slowly.
- STEP 6
Transfer the cheesecake in its tin to a wire rack to cool completely, then refrigerate for at least 6 hours before serving.
- STEP 7
To serve, carefully unmould and cut into slices, using a very sharp knife dipped in hot water between each cut.