Method

1. Heat the oven to 170C/325F/Gas 3.
2. Bash the digestive biscuits into crumbs. Melt the butter over a low heat and mix in the biscuit crumbs and lemon zest. Lightly grease a 25cm/10in loose-bottomed cake tin and press the crumbs into the base and up the sides slightly.
3. Mix together the cream cheese, pumpkin flesh, sugar, cinnamon and nutmeg until smooth. Beat the eggs and fold into the pumpkin mixture. Turn into the tin and bake in the oven for 90 minutes until the surface is set but the underneath still slightly squidgy.
4. Take the cheesecake out of the oven and let it cool in the tin. When cool, turn it on to a serving plate, cover with foodwrap and chill overnight.
5. Whip the double cream until thick and fold in the yoghurt and the lemon juice. Spread over the top of the cheesecake and serve at room temperature.