Ingredients

Step by step

1. Put the frozen blueberries, sugar and lemon juice (reserve the zest) in a large saucepan. Set over a medium heat and bring to a simmer, stirring occasionally, until the sugar has dissolved and the blueberries have started to break down (about 15-20 minutes). Remove from the heat and whizz to a purée using a stick blender (or transfer to an upright blender). Transfer 150g to a small airtight container. Leave to cool, then cover and set aside in the fridge until ready to serve.

2. Put the gelatine leaves in a bowl of cold water and leave to soak for 5 minutes. Meanwhile, return the larger quantity of purée to a gentle simmer. Squeeze the water from the gelatine leaves and stir them into the purée, off the heat, until dissolved. Strain into a large bowl, discarding any pulp left in the sieve, and leave to cool completely (1-2 hours at room temperature).

3. In a large bowl, whip 300ml of the double cream and lemon zest to almost soft peaks. Using a balloon whisk, carefully fold the cream through the cooled berry purée until combined. Pour in the remaining cream and fold through with the balloon whisk to a soft dolloping consistency. Divide evenly among 6 small glasses or ramekins (about 220-250ml each), then set in the fridge for at least 3 hours, or overnight.

4. For the crumble, preheat the oven to 200°C, fan 180°C, gas 6. Put the chopped hazelnuts, flour and a pinch of salt in a large bowl. Rub in the butter using your fingertips to a crumb-like consistency and until there is no loose flour at the bottom of the bowl. Rub in the brown sugar and chopped thyme. Spread out on a baking tray and bake for 15-20 minutes or until dark golden-brown. Leave to cool on the tray, then store in an airtight container until ready to serve.

5. To serve, remove the mousses from the fridge, spoon over the reserved chilled blueberry purée and scatter over some of the hazelnut crumble and extra thyme.