For the biscuit base
- 280g/10oz digestive biscuits
- 65g/2¼oz granulated sugar
- ¼ tsp ground cardamom
- 128g/4½oz unsalted butter, melted
- large pinch sea salt
For the mango custard filling
- 100g/3½ oz granulated sugar
- 2 tbsp plus ¼ tsp powdered gelatine
- 120ml/4fl oz double cream
- 115g/4 oz cream cheese, at room temperature
- 850g tin Alfonso mango pulp
- large pinch sea salt
To make the biscuit base, finely crush the biscuits by putting into a sealed plastic bag and bashing with a rolling pin (alternatively, pulse to crumbs using a food processor). Transfer to a mixing bowl and add the sugar, cardamom and salt, stirring well to combine.
Pour the melted butter over the biscuit crumbs and mix, until thoroughly combined. Put half the crumb mixture in a 23cm/9in metal pie tin, and press evenly with your fingers. Build up the sides of the tin, compressing the base as much as possible to prevent it crumbling. Repeat with the rest of the mixture in the second tin.
Preheat the oven to 160C/325F/Gas 3. Put the pie bases in the freezer for 15 minutes. Remove and bake for 12 minutes, or until golden brown. Transfer to a wire rack to cool.
To make the filling, pour 177ml/6fl oz of cold water into a large bowl. In a separate bowl, mix the gelatine with half the sugar and sprinkle over the water. Leave to stand for a couple of minutes.
Meanwhile, whip the cream with the remaining sugar to form medium stiff peaks. Set aside.
Heat about a quarter of the mango pulp in a saucepan over a medium-low heat, until just warm. Make sure you do not boil it. Pour into the gelatine mixture and whisk, until well combined. The gelatine should dissolve completely. Gradually whisk in the remaining mango pulp.
Beat the cream cheese in a bowl, until soft and smooth. Add to the mango mixture with the salt. Blend the mixture using a hand blender, until completely smooth. Gently tap the bowl on the kitchen counter once or twice to pop any air bubbles.
Fold about a quarter of the mango mixture into the whipped cream using a spatula. Repeat with the rest of the cream, until no streaks remain.
Divide the filling between the cooled bases, using a rubber spatula to smooth out the filling. Refrigerate overnight, or for at least 5 hours, until firm and chilled.