Wash and peel blueberries. Add half of the blueberries to a saucepan, sprinkle with sugar, add juice and let simmer for a few minutes. Strain blueberries through a sieve, pass and return to heat. Add cornstarch and a little cold water to fruit puree and bring to a boil. Carefully fold in remaining blueberries, boil again and remove from heat. Set aside approximately 4 tablespoons of blueberry mixture for garnish.
Remove crusts from white bread and lay out edges of ramekins with it. Fill ramekins with blueberry mixture and cover well with remaining white bread, so berry filling is completely sealed. Chill for at least 4 hours.
Garnish with remaining blueberries and serve in ramekins.