First make the pastry by putting the flour, butter, icing sugar and egg in a blender and pulsing until it forms a ball of dough (there is no need for water). Take the pastry out of the blender and wrap in cling film and chill in the fridge for at least 2 hours.
To make the crumble rub the flour and butter together until it resembles rough breadcrumbs. Add in the sugar and ground almonds and set aside.
Trim the rhubarb and cut into slices. Place in a pot with the ginger, cranberry juice and caster sugar (add more if needed). Heat gently and simmer until the rhubarb is tender.
Next roll the chilled pastry between two sheets of cling film to prevent it from sticking. Grease the individual tart tins and line with pastry and bake in a pre-heated oven at 180°C for about 10 minutes or until the pastry is a pale golden colour.
Fill the cooked tartlets with the stewed rhubarb. Place some of the crumble mixture on top and sprinkle with some flaked almonds and place in the hot oven for 10-15 minutes or until the crumble is golden.
To serve, remove the tart from the mould and serve with some whipped cream and a little rhubarb to garnish.