Prep the pan: Line a rimmed baking sheet with parchment paper.
Make sure the paper goes up the sides a bit so you can lift the bark out later.
Mix the base: In a bowl, whisk the Greek yogurt, honey or maple syrup, vanilla, and a pinch of salt until smooth. If using protein powder, sift it in and whisk thoroughly to avoid clumps.
Add texture: Stir in chia seeds or ground flax if using. These help firm the bark and add fiber.
Spread it out: Pour the mixture onto the lined sheet and spread it into an even layer, about 1/4 inch thick.
Thinner layers freeze faster and break more cleanly.
Top it off: Scatter blueberries over the surface. Gently press them in so they stick. Sprinkle nuts and any extras like coconut or mini chocolate chips.
Optional swirl: Dot a few teaspoons of blueberry jam over the top and swirl lightly with a toothpick or knife for a marbled look.
Freeze: Place the tray flat in the freezer for 2–4 hours, or until completely firm.
Break and serve: Lift the slab out by the parchment and break into pieces.
Enjoy right away or store for later.