Heat oven to 375°F.
Place 2 cups of the flour, the baking powder, baking soda and salt into a food processor; lock cover and pulse once or twice to combine. In a large bowl, toss together the fruit, sugar, lemon juice and cinnamon along with the remaining 2 ½ Tablespoons flour. Transfer mixture to a deep 9” x 13” baking dish and set aside.
Scatter the cold butter pieces over the flour mixture in the food processor, lock the cover, and pulse until mixture resembles coarse crumbs – stopping once or twice to scrape down the sides.
Transfer flour/butter mixture to a medium-large bowl. Add the buttermilk, stirring just to combine.
Spoon or scoop the batter onto the fruit mixture to evenly disperse, allowing some pockets of fruit to “peek out” from below.
Bake until the biscuit topping is golden and the fruit is juicy and bubbling – about 45 to 55 minutes. Let cool slightly before serving. Serves 6 or more.