Method
Divide the crushed ginger biscuits evenly between 10 mini (3-inch) tart tins, pressing evenly into the base to mimic a pie base.
Heat the milk and cream in a saucepan and bring to the boil.
Remove from the heat and stir in the panna cotta powder and lime zest, whisking continuously until the mix returns to the boil.
Allow the panna cotta mix to cool slightly then pour over biscuit bases, leaving a small amount of room at the top of the mould for the jelly. Chill until set.
While the panna cotta is setting, prepare the jelly. Dissolve the cubes of lime jelly tablet in 140ml (1/4 pint) boiling water then top up with 140ml cold water. Pour the jelly over the set panna cotta and return to the fridge until set.
To serve, remove the key lime pies from the tart tins and top with fresh blueberries.