How to Make It
Preheat the oven to 400°. In a large bowl, whisk the flour with the baking powder, baking soda, salt and 1 tablespoon of the granulated sugar. Using 2 knives or a pastry blender, cut in the butter until it is the size of small peas. Make a well in the center and add the buttermilk. Using a wooden spoon, stir until a crumbly dough forms.
Transfer the dough to a lightly floured surface and knead 2 or 3 times, just until evenly moistened. Pat the dough 1/2 inch thick. Using a 2 3/4-inch round biscuit cutter, stamp out as many rounds as close together as possible. Gather the scraps, knead gently and cut out 1 or 2 more biscuits.
Transfer the biscuits to a baking sheet. Brush the tops lightly with buttermilk and sprinkle with the coarse sugar. Bake for 10 minutes. Reduce the heat to 350° and bake for about 20 minutes longer, or until the biscuits are golden and cooked through. Let cool.
In a medium bowl, toss the berries with the remaining 2 tablespoons of granulated sugar and let stand for 5 minutes. Split the biscuits horizontally and transfer the bottom halves to a large platter or plates. Top with scoops of ice cream and the berries. Replace the biscuit tops and serve right away.