In a medium bowl, combine the Greek yogurt, honey, and vanilla extract. Mix well until smooth and creamy.
Gently fold in the huckleberries, being careful not to crush them.
Line a baking sheet with parchment paper. Pour the yogurt mixture onto the sheet and spread it out evenly to about 1/2 inch thick.
Sprinkle granola and chopped nuts over the top, if using.
Place the baking sheet in the freezer and freeze for at least 4 hours or until completely solid.
Once frozen, remove from the freezer and let it sit for a few minutes to soften slightly. Cut or break into pieces and serve.