Mixed Berry Buckle

Step 1: For the Streusel: Stir all ingredients in a bowl until no dry spots remain and mixture forms clumps.  Refrigerate until streusel is firm, at least 10 minutes.  Keep refrigerated until ready to use.

Step 2: For the Cake: Adjust oven rack to middle position and heat oven to 350 degrees F.  Grease a 9-inch round cake pan, line with parchment paper, grease parchment, and flour pan.

Step 3: Whisk milk, eggs, melted butter, and vanilla extract in bowl until well combined.  Whisk flour, 1/4 cup sugar, baking powder, lemon zest, and salt together in a large bowl.  Stir milk mixture into flour mixture until just combined.

Step 4: Toss blackberries, blueberries, and raspberries with remaining 1/4 cup sugar in separate bowl until coated.  Using rubber spatula, gently fold half of berry mixture into batter until evenly distributed.  Transfer batter to prepared pan and spread to edges of pan with spatula.  Sprinkle remaining half of berry mixture evenly over top.

Step 5: Break streusel into pea-sized crumbs and distribute evenly over berries.  Bake until top of buckle is golden brown and a toothpick inserted into the center comes out clean, about 50 minutes, rotating pan halfway through baking.  Let buckle cool in pan on wire rack for 2 hours.

Step 6: Run paring knife around edges of pan to release buckle from pan.  Please inverted plate on top of pan (do not use plate or platter on which you intend to serve the buckle).  Invert buckle, remove pan, and discard parchment.  Reinvert buckle onto serving platter.  Cut into wedges and serve.

Enjoy this delicious, family-sized dessert this holiday season!