In a mixing bowl, combine blueberries and cherries. Juice one lemon into the bowl. Sprinkle sugar and cornstarch on the berries. Toss together until sugar and cornstarch are absorbed. Pour into baking dish.
Add in flour, sugar, baking powder, and vanilla extract to the butter. Use a pastry blender to combine until you have a sugar cookie-like texture.Gradually pour the milk into the bowl with the dough mixture.
Pour the biscuit batter on top of the fruit. Try to cover all of the berries with the batter.
Bake for 40-45 minutes. Serve warm with a scoop of vanilla ice cream and/or whipped cream. Enjoy!