Grease and line a 23cm springform baking pan/tin with non-stick baking paper. Crush the biscuits until they look like fine breadcrumbs, add the butter and lemon zest, mix thoroughly and then press into the bottom and sides (if you like the biscuit base on the sides) of the baking pan/tin. Place in the freezer for about 30 mins.
Add 2 Tbsp. water in a heatproof bowl over a pan of simmering water, add the gelatin and stir until completely dissolved (or just follow the instructions on the packet).
While the gelatin is cooling, beat the cream cheese, sugar and lemon juice in a mixing bowl or if using a food processor, pulse until smooth, scraping down the sides of the bowl every few minutes so that you don’t have any lumps at the end and beating again until smooth.
Pour into prepared tin, refrigerate until set, and then decorate by sprinkling the raspberries over the top, and brush with the warmed jam.