Line a rimmed cookie sheet with parchment or waxed paper.
In a large bowl, combine the yogurt, protein powder, sweetener, and vanilla extract. Whisk together until smooth and creamy.
Add the berries and mash them slightly with a fork or a potato masher. Leave some larger pieces.
Spread the mixture on the prepared baking sheet to about 1/3 to 1/2 inch thick. Place in the freezer until firm.
In a small microwave-safe bowl, melt the white chocolate chips on high, stirring every 20 to 30 seconds. Once they are halfway melted, remove and keep stirring until completely melted.
Drizzle lightly over the frozen bark. Let sit at room temperature for 2 minutes or so before cutting into squares.
Notes
Storage Information: Keep the bark in a covered container in the freezer for up to 3 months.