Place the blueberries and lemon juice into a small saucepan over a gentle heat. Cook until the blueberries are beginning to burst open and are softened.
Using a hand blender, blend the blueberries to a smooth purée and leave to cool.
To make the tart cases, place the biscuits and hazelnuts into a food processor and blend to a fine crumb consistency.
Add the melted butter and blend until well mixed in. Spoon out the mixture into the tartlet tins and press into the base and sides of the tins. Transfer to the fridge and chill for one hour.
Meanwhile, in a large bowl, whip the cream until it forms soft peaks.
Place the lemon curd into a bowl and add the blueberry purée and mix together well.
Add the blueberry mixture to the whipped cream and fold in gently, leaving a marbled, 'blueberry ripple' effect.
Carefully turn the chilled shortbread tart cases out of their tins onto plates and spoon the blueberry and lemon cream inside.
To serve, scatter over the extra blueberries and sprinkle with a little lemon zest to garnish.