Make the crust: Place the digestive biscuits in a sealed plastic bag and crush them with a rolling pin until you have fine, sandy crumbs with no large chunks. Tip the crumbs into a bowl, pour over the melted butter and caster sugar, then stir until every grain of biscuit is coated and the mixture looks like wet sand. Press this firmly into the base of a 20cm square tin lined with parchment paper. Use the bottom of a glass to really compact it down — you want a solid, even layer. Pop the tin into the fridge while you prepare the filling.

Whip the cream: Pour the double cream into a large, chilled bowl and whisk with an electric mixer until soft peaks form. You’ll know it’s ready when you lift the beaters and the cream holds a gentle curl that flops over slightly. Set this aside in the fridge for a moment.

Beat the cream cheese: In a separate large bowl, beat the softened cream cheese with the sifted icing sugar and vanilla extract until the mixture is completely smooth and glossy, with no streaks of white sugar visible. The texture should feel silky and light, not dense.

Fold everything together: Take the whipped cream from the fridge and add it to the cream cheese mixture in three additions. Use a large metal spoon or a spatula to fold gently — cut through the centre, scrape around the edge, and turn the mixture over. Stop as soon as the last streak of white disappears, otherwise you’ll knock the air out and lose the lovely light texture.

Assemble the bars: Retrieve the chilled crust from the fridge. Spoon the creamy filling over the top and spread it evenly with an offset spatula. Tap the tin gently on the counter to release any air bubbles — you’ll see a few tiny pops appear on the surface. Cover loosely with cling film and return to the fridge for at least 4 hours, though overnight is best.

Make the blueberry topping: While the bars set, combine the blueberries, granulated sugar, and lemon juice in a small saucepan over medium heat. Stir gently until the berries begin to soften and release their deep purple juice — you’ll hear a soft popping sound as the skins burst. Simmer for 5 minutes, then stir in the cornflour slurry. Continue cooking for another 2 minutes until the mixture thickens and coats the back of a spoon. Remove from the heat and allow to cool completely before you use it.

Slice and serve: Once the bars are fully set, lift them out of the tin using the parchment paper. Run a sharp knife under hot water, dry it, and slice into 12 neat bars. Spoon a generous dollop of the cooled blueberry compote over each bar just before serving.