Line a half-sheet baking pan with parchment paper or a silicone baking mat. Make sure it lies completely flat and covers the full surface.
In a medium bowl, stir together the Greek yogurt, honey, and vanilla extract until smooth and fully combined. Taste it before you spread - it should be lightly sweet.
Pour the yogurt mixture onto the prepared pan. Use a rubber or offset spatula to spread it into an even layer, about 1/4 inch thick. Work from the center outward.
Arrange the sliced strawberries, blueberries, and raspberries across the yogurt surface. Press each piece down slightly so it embeds into the yogurt.
Place the pan in the freezer, uncovered, for at least 2 hours - or until the yogurt is completely firm when you press the center firmly with one finger.
Lift the parchment off the pan. Break the bark into irregular pieces with your hands, or use a sharp knife for cleaner edges. It should snap with a satisfying crack.
Serve the bark straight from the freezer. Transfer any leftovers to an airtight freezer-safe bag or container right away. Keep everything in the freezer - not the fridge.
