Add the blueberries to a small sauce pan together with the lime or lemon juice. Cover with a lid and bring to a simmer. Cook for a few minutes until the blueberries have all popped. Allow to cool completely.
In a mixing bowl combine together the yogurt, honey and vanilla extract.
Add the blueberry sauce and mix well.
Line a shallow baking dish with parchment paper and pour the yogurt mix on top.
Sprinkle with the blackberries and some fresh blueberries. Garnish with a few violas id available.
Freeze for 4 to 6 hours until completely frozen.
Cut or break into 2 inch bars and serve with lost of napkins.