Line a baking sheet with parchment paper, leaving enough overhang on the edges for easy removal later.
In a mixing bowl, combine the Greek yogurt, honey, and vanilla extract. Stir until the mixture is smooth and well combined.
Pour the yogurt mixture onto the prepared baking sheet and spread it evenly with a spatula to your desired thickness (about ½ inch thick).
Scatter the mixed berries evenly over the yogurt layer, pressing them gently into the yogurt.
If using, sprinkle granola over the top for added crunch.
Place the baking sheet in the freezer and let it freeze for about 3 hours, or until solid.
Once frozen, remove the yogurt bark from the freezer. Lift the parchment paper out of the pan and place it on a cutting board.
Use a sharp knife to cut the bark into pieces of your desired size.