Line the inside of 25cm round spring-form tin with a single sheet of buttered foil. Beat the egg and the sugar with an electric whisk until light and fluffy. Add the syrup and lemon zest, beat until very thick. Sift the flour, then fold this through the whipped egg until evenly combined. Spoon into the tin, spread evenly, covering the base thinly. Bake in preheated 180°C (160° C fan-assisted) oven for 10-12 mins until golden and firm.
Cut the tinned cherries in half, removing any stones, press dry on paper towels and stir with the jam. Spread this mixture evenly over the sponge and set aside while making the crumble mixture. Put the dry ingredients into a bowl and rub the butter and the tablespoon of milk through until the mixture resembles dry pastry crumbs. Leave at room temperature while making the filling.
Beat the cream cheese with the icing sugar, cornflour and vanilla until light and fluffy. Beat the eggs together in a separate bowl, then slowly beat the eggs into the cream cheese mixture. Stop as soon as the eggs are barely combined as you do not want to aerate the mixture any more. Stir in the cream until it disappears. Spoon the cream cheese mixture into the tin and bake for 20 mins at 180°C (160° C fan-assisted).
At this point, open the oven door, sprinkle the crumble mixture over the top, close the oven door and bake for a further 30 – 40 mins. At this stage only the very centre should wobble slightly. Remove Cherry Crumble Cheesecake from the oven, cool at room temperature, then refrigerate for 3-4 hours until firm and chilled.