Best Mixed Berry Cobbler. In a medium mixing bowl whisk flour sugar brown sugar baking powder and salt together. Preheat the oven to 350F and spray a 9x13 baking dish with nonstick spray.
Using a pastry blender or a fork mix butter into flour mixture until crumbly. Preheat the oven to 350F and spray a 9x13 baking dish with nonstick spray. Spread berries over the bottom of the baking sheet in an even layer.
Add the melted butter and vanilla and whisk until combined and a smooth batter.
Step 2 Melt butter in a 9 x 13 glass dish. Step 1 Mix berries and 12 cup sugar and set aside. Let stand for 30 minutes. Sprinkle remaining cup of berries.