Lay a piece of parchment paper over a baking sheet.
Mix together the Greek yogurt, honey, and vanilla in a large bowl until combined well.
Spread the Greek yogurt out in an even layer onto the parchment paper. (Do not make your yogurt layer too thin, or it will crumble under the weight of the berries.)
Place the sliced strawberries along the surface of the yogurt, then add the blueberries.
Sprinkle on the cacao chips. Optional: drizzle yogurt bark with extra honey at this point, if desired.
Place the sheet pan into the freezer to set for at least 3 hours. (Overnight would be best.) The longer it has to set, the easier it will be to break into pieces.
Store in an airtight container in the freezer for up to a week.