Prepare the base: Preheat your oven to 160°C (140°C fan). Line the base of a 23cm springform tin with parchment paper. Crush the digestive biscuits into fine crumbs — you want a texture resembling wet sand, with no large chunks. Pour the melted butter and caster sugar over the crumbs and stir until every grain is coated. Press the mixture firmly into the base of the tin, using the bottom of a glass to create an even, compact layer. Bake for 10 minutes until the base is fragrant and lightly golden at the edges. Set aside to cool completely.

Make the filling: In the bowl of a stand mixer fitted with the paddle attachment, beat the room-temperature cream cheese on low speed for one minute until smooth and fluffy, with no lumps. Add the caster sugar and beat for another minute — the mixture should look glossy and feel silky between your fingers. Scrape down the sides of the bowl thoroughly. Add the eggs one at a time, beating on low after each addition until just incorporated. The mixture should be uniformly pale yellow and smooth.

Add the flavourings: Pour in the vanilla bean paste, lemon zest, and lemon juice. Mix on low until combined — the aroma at this stage is sharp and invigorating. Add the double cream and mix until the batter is homogenous, then fold in the sifted plain flour using a spatula. The final batter should be thick, creamy, and pourable, with a slight sheen.

Bake the cheesecake: Pour the filling over the cooled biscuit base. Gently tap the tin on the worktop three times to release any air bubbles. Bake for 50-55 minutes. The cheesecake is ready when the edges are set and slightly puffed, but the centre still wobbles like a jelly when you gently shake the tin. You should see a faint jiggle in the middle 5cm area. Turn off the oven, crack the door open, and leave the cheesecake inside for one hour. This slow cooling prevents cracking.

Chill thoroughly: Remove the cheesecake from the oven and run a thin knife around the edge of the tin to release any sticking. Allow it to cool completely on a wire rack at room temperature, then refrigerate for at least 6 hours, preferably overnight. The surface should feel firm to the touch, and the centre should be fully set when sliced.

Make the blueberry topping: In a small saucepan, combine the blueberries, caster sugar, and lemon juice. Cook over medium heat, stirring occasionally. After about 5 minutes, you’ll hear the berries begin to pop and release their deep purple juice. The mixture will become syrupy and fragrant. Stir in the cornflour slurry and continue cooking for 2 minutes until the sauce thickens to a glossy, jammy consistency that coats the back of a spoon. Remove from heat and cool to room temperature.

Assemble and serve: Once the cheesecake is fully chilled, release the springform tin and transfer the cheesecake to a serving plate. Spoon the blueberry topping over the centre of the cheesecake, allowing it to cascade naturally down the sides in uneven rivulets. For a polished, restaurant-style finish, use a palette knife to create a smooth, even layer across the top, leaving a 1cm border of plain cheesecake visible at the edge. Slice with a hot, dry knife for clean cuts.