Preheat oven to 350 degrees. Grease a 2 quart baking dish.
Stir berries together with sugar, cornstarch, nutmeg an lemon juice and add to baking dish.
In a food processor, combine butter and sugar, pulsing until fluffy. Mix in flour, baking powder, salt and buttermilk/milk, pulsing to combine.
Top berries with dry mixture. Bake for 55 minutes. Topping should be golden brown.
I made a few changes to the original recipe, all reflected in the recipe above: our berry mixture was too runny, so an additional tablespoon of cornstarch is necessary as well as an extra 15 minutes of baking time. For the berries, I used 2 pints of blueberries and 2-6 oz. containers of blackberries.
Adapted from an original recipe on Recipe Lion