Mallow, blueberry & lemon

Makes 14

70g unsalted butter, plus extra for greasing

200g digestive biscuits

400g blueberries

350g caster sugar juice of 2 unwaxed lemons, plus peel of 2 unwaxed lemons, grated into spirals

500g cream cheese

400g condensed milk

115ml cold water

¼ tsp cream of tartar

¼ tsp fine salt

2 egg whites

25 x 20cm baking tin baking paper

Grease and line the baking tin with baking paper. In a food processor, crush the biscuits until fine crumbs. In a microwaveable bowl, melt the butter in the microwave for 1 min until a liquid. Mix the butter into the crushed biscuits, then transfer to the prepared tray. Press the biscuit mixture down, using the back of a spoon, until it covers the entire bottom of the tin and is smooth and flat. Leave to chill for 30 mins.

In a liquidiser or food processor, blend the blueberries until a juice. Strain the juice through a sieve into a jug, discarding the pulp. Pour the reserved liquid into a small saucepan and add 100g of the caster sugar. Simmer until the sugar dissolves, then bring to the boil and heat on a high heat for 1 min. Spread the blueberry mixture over the biscuit base, making sure it is even, then leave to chill for 1 hr. In a large bowl, combine the lemon juice, cream cheese and condensed milk, then whisk for 1-2 mins until very thick. Carefully transfer the mixture to the baking tin, making sure the layer of blueberry liquid stays in place. Level off the top with a spatula, then leave to chill for 2 hrs.

To make the marshmallow, combine the remaining 250g of caster sugar, the water, cream of tartar and salt in a large saucepan. Without stirring, bring to a boil and cook on a high heat for 5-6 mins until 115°C on a kitchen thermometer.

While the sugar syrup cools slightly, whisk the egg whites in a food processor until soft peaks form and so the mixture does not slip around in the bowl. With the whisk on its lowest setting, whisk in the sugar syrup in a slow, but steady, pour. Once the sugar is incorporated, whisk on high for 5-6 mins until stiff peaks form.

Criss-cross small cuts in the top of the chilled cream cheese topping so the marshmallow does not slip when it is set on top. Cover the topping with the marshmallow, smoothing the surface down with a spatula. Leave to chill for 2 hrs, then slice into 14 thin slices and serve, decorated with the lemon peel spirals.