2 cups fresh or frozen mixed berries (or any 1 berry – strawberries, raspberries, blueberries, etc.)
2 tsp. cornstarch
1 large egg yolk
1 1/2 cups all-purpose flour
3/4 cup granulated sugar, divided
1 Tbsp. lemon juice
1 tsp. lemon zest
1/8 tsp. salt
1/2 cup salted butter, chilled and cut into cubes
1 Tbsp. raw turbinado sugar
1 tsp. vanilla extract
Preheat oven to 375 degrees F. Generously butter an 8x8-inch baking dish and set aside.In a large mixing bowl, whisk together flour, 1/2 cup granulated sugar, baking powder, salt and lemon zest. In a small mixing bowl, whisk egg yolk and vanilla.
Add egg mixture and cold butter cubes to flour mixture. With a fork, pastry cutter, or your fingertips, cut mixture together until it resembles coarse crumbs. Gently press a little over half of the mixture into the prepared 8x8 dish.In a separate medium bowl, whisk together remaining 1/4 cup granulated sugar and 2 tsp. cornstarch. Stir in lemon juice then add berries. Toss mixture to evenly coat.
Pour into baking dish and spread evenly over bottom crust. Sprinkle remaining crumb mixture over berry layer (I pressed some of the mixture together in my hands while sprinkling to make larger crumbs). Sprinkle raw turbinado sugar evenly over top.
Bake in preheated oven for 35-38 minutes, or until top is golden brown. Allow to cool for 20-30 minutes before cutting into squares. Store bars in an airtight container in refrigerator.Enjoy!