Line a sheet pan. Use a rimmed baking sheet and line it with parchment paper.
This prevents sticking and makes it easy to lift the bark out later.
Mix the base. In a medium bowl, whisk the Greek yogurt, honey or maple syrup, vanilla, and a pinch of salt until smooth and evenly sweetened.
Spread it out. Pour the yogurt mixture onto the lined pan and spread it into an even layer, about 1/4 inch thick. Thinner sets faster and breaks more easily; thicker gives a creamy bite.
Add the blueberries. Scatter blueberries evenly over the yogurt. Gently press them in so they stick once frozen.
Freeze. Place the pan flat in the freezer and freeze for 3–4 hours, or until completely firm.
Break into pieces. Lift the hardened slab by the parchment and place it on a cutting board.
Break into shards by hand or use a sharp knife to cut into squares.
Portion and store. For 100-calorie servings, aim for about 16 pieces from the batch. Transfer to a freezer-safe bag or airtight container.