Preheat oven to 400°F. Grease (1) 9x9-inch baking dish. Set aside.
In a large bowl, gently stir the blackberries with the sugar, flour, salt, and lemon juice. Add to the prepared baking dish, then dot with the 2 tablespoons of butter.
4 heaping cups fresh or frozen blackberries, 1 cup granulated sugar, ½ cup all-purpose flour, ¼ teaspoon fine sea salt, 2 teaspoons lemon juice, 2 tablespoons unsalted butter
Bake for 15 minutes, or until the berries are juicy and bubbly.
While the filling bakes, make the biscuit topping. In a medium bowl, whisk together the flour, sugar, baking powder, and salt. Use a pastry blender or two knives to cut the butter into the flour mixture until the mixture resembles coarse crumbs.
1 cup all-purpose flour, 3 tablespoons granulated sugar, 2 teaspoons baking powder, ¼ teaspoon fine sea salt, ¼ cup unsalted butter
In a small bowl or measuring cup, whisk together the milk and egg. Using a fork, stir this into the flour mixture until no dry ingredients remain.
⅓ cup milk, 1 large egg
Remove the filling from the oven and use a spoon to drop spoonfuls of the biscuit dough across the hot filling. Return to the oven and continue baking for an additional 20-25 minutes, or until the topping is golden.
Allow to cool before serving with a scoop of vanilla ice cream or a dollop of whipped cream.
Notes
Storage
Best served on the day it is made, but leftovers can be stored in an airtight container in the refrigerator for up to 3 days. I recommend reheating leftovers in the microwave for 30-60 seconds before enjoying.