Make the biscuit base. Place the digestive biscuits in a sealed food bag and crush them with a rolling pin until you have fine crumbs that look like wet sand. Tip the crumbs into a bowl, pour over the melted butter and caster sugar, and stir until every crumb is coated and the mixture feels clumpy when pressed between your fingers.

Form the crust. Tip the buttery crumbs into a 23cm loose-bottomed tart tin. Press them firmly and evenly into the base and up the sides using the flat bottom of a glass. The crust should feel compact and solid, not crumbly. Place the tin in the fridge to chill while you prepare the filling.

Make the blueberry compote. In a small saucepan, combine the blueberries, granulated sugar, cornflour, and water. Set over a medium heat and stir gently. After about 3 minutes, you will hear a soft popping sound as the berries begin to burst. The mixture will thicken and turn a deep, glossy purple. Simmer for 2 minutes, then remove from the heat and let it cool completely.

Whip the cream. Pour the double cream into a large, chilled bowl. Using an electric whisk, beat it until soft peaks form. When you lift the whisk, the cream should hold its shape briefly before flopping back down. Do not over-whip, or it will become grainy.

Mix the lemon filling. In a separate large bowl, beat the softened cream cheese and sifted icing sugar together until smooth and glossy, with no lumps. Add the lemon zest, lemon juice, and lemon curd. Beat again until the mixture is pale yellow and smells wonderfully sharp and fresh.

Fold everything together. Gently fold the whipped cream into the lemon cream cheese mixture using a large metal spoon. Use a figure-of-eight motion, cutting through the centre and bringing the mixture up from the bottom. Stop as soon as you cannot see any streaks of white; the filling should be light, airy, and uniform in colour.

Assemble the tart. Spoon half of the lemon filling into the chilled biscuit base and spread it into an even layer. Dollop the cooled blueberry compote over the filling and spread it gently, leaving a small border around the edge. Spoon the remaining lemon filling on top and smooth the surface with a palette knife or the back of a spoon. The top should look smooth and pale yellow.

Chill and set. Cover the tart loosely with cling film and refrigerate for at least 4 hours, though overnight is better. The filling should feel firm and bounce back slightly when you gently press the centre. When you slice through it, the layers should hold their shape cleanly.

Decorate and serve. Just before serving, top with fresh blueberries and a few mint leaves if you like. Run a warm, dry knife around the edge of the tin before releasing the tart. The crust should feel firm and buttery, and the filling should be silky and smooth.