In a medium bowl, combine the Greek yogurt, honey, and vanilla extract, stirring until completely smooth and well combined. The honey should be fully incorporated so there are no streaks—this ensures even sweetness throughout the bark. I like to taste a small spoonful at this point to adjust the sweetness if needed, since freezing will mute the flavors slightly.

Line a baking sheet (roughly 9x13 inches or similar) with parchment paper. Pour the yogurt mixture onto the lined tray and use an offset spatula or the back of a spoon to spread it into an even layer about 1/4 to 1/2 inch thick. A thinner layer will freeze faster and be more brittle; a thicker layer will be creamier when you bite into it—choose based on your preference.

Scatter the granola and mixed berries evenly across the yogurt layer, pressing them down gently so they adhere to the surface. Place the tray in the freezer and freeze for 2 to 3 hours until the yogurt is completely solid and set. I find that checking after 2 hours helps me catch it at the perfect texture—firm enough to cut but not rock-hard.

Remove the frozen bark from the freezer and let it sit at room temperature for 2 to 3 minutes to slightly soften the edges, which makes cutting easier and prevents cracking. Using a sharp knife, cut the bark into bite-sized pieces or shards—roughly 2 to 3 inch pieces work well. Serve immediately or store in an airtight container in the freezer for up to 2 weeks.