Prepare the Filling: Wash the blueberries and then pat them thoroughly dry with layers of paper towels. Transfer them to a mixing bowl. Add the thick yogurt. Using a silicone spatula, gently fold until each blueberry is evenly coated. The mixture should be clumpy and hold together, not runny.

Freeze Until Solid: Line a baking sheet or tray with parchment paper. Use a spoon or small cookie scoop to portion the yogurt-coated blueberries into small clusters (about 8-10 berries per cluster). Place them on the prepared sheet, leaving a little space between each. Freeze for at least 2 hours, or until the clusters are completely rock-solid.

Make the Chocolate Shell: About 10 minutes before the clusters are ready, prepare the chocolate. Combine the dark chocolate and coconut oil in a heatproof bowl. Set the bowl over a pot of barely simmering water (ensure the bottom of the bowl doesn't touch the water). Stir frequently until completely melted and smooth. Remove from heat and let cool until it's just barely warm to the touch.

Dip and Set: Remove the frozen blueberry clusters from the freezer. Working quickly, use a fork to spear a cluster, dip it into the melted chocolate, and swirl to coat completely. Let the excess chocolate drip back into the bowl, then place the cluster back onto the parchment paper. Repeat with remaining clusters.

Final Set: Once all clusters are dipped, place the tray in the refrigerator for 10-15 minutes to allow the chocolate shell to set completely. For longer storage, transfer to an airtight container and keep in the freezer.