• Preheat oven to 375° and spray a 13 x 9 or a 3 quart baking dish with a non stick spray right before adding the berry mixture.

For the Berry Filling

• Pour berries into a large bowl and rinse. 
• Sprinkle berries with sugar, lemon juice, and corn starch. Stir and let sit for 10 minutes. Stir one more time.
  
• Pour berries into prepared baking dish.

For the Topping

• In a medium mixing bowl, whisk flour, sugar, brown sugar, baking powder and salt together.
• Using a pastry blender, or a fork, mix butter into flour mixture until crumbly.
• Pour boiling water into flour mixture and stir until combined.
• Spoon mixture over berries and spread gently making sure berries are covered completely.
• Sprinkle additional sugar on top of batter.
• Bake uncovered for 55-60 minutes or until topping is cooked thoroughly and has started to brown.
• Serve warm topped with vanilla ice cream.