Brown sugar-sweetened shortcakes with fresh, ripe peaches and a lightly sweetened cream topping that’s reminiscent of crème fraîche is the perfect ending to a summer meal.
To prepare fruit: Toss peaches with 2 tablespoons brown sugar in a medium bowl and set aside, stirring occasionally to help dissolve the sugar.
To prepare shortcakes: Preheat oven to 425°F. Line a baking sheet with a nonstick silicone baking mat or parchment paper or coat with cooking spray.
Place white whole-wheat flour, all-purpose flour, 1/3 cup brown sugar, baking powder, baking soda and salt in a food processor; pulse to combine. Add butter and oil and pulse until the mixture resembles coarse sand. Add buttermilk and vanilla. Process until the dough comes together. (Alternatively, combine flours, brown sugar, baking powder, baking soda and salt in a large bowl. Add butter; with your fingers, quickly rub it into the dry ingredients until the pieces are smaller but still visible. Add oil, buttermilk and vanilla and stir with a fork until the dough comes together.)
Using a rubber spatula, transfer the dough to a floured surface. Knead several times so the dough comes together. Pat the dough into an approximate 6-by-12-inch rectangle, about inch thick. Cut out 6 rounds with a 3-inch biscuit cutter (or cookie cutter) dipped in flour; press it straight down without twisting so the shortcakes will rise evenly when baked. Pat the remaining dough back into a 6-by-3-inch oval and cut out 2 more biscuits. (Discard any remaining scraps of dough.) Place the shortcakes on the prepared baking sheet. Brush the tops with water and sprinkle with raw sugar (if using).
Bake the shortcakes until the bottoms are golden brown and the tops are beginning to color, 13 to 15 minutes. Transfer to a wire rack to cool slightly.
To prepare topping: Beat cream in a medium bowl with an electric mixer or whisk until soft peaks form, 1 to 2 minutes. Fold in sour cream until combined.
To serve, split the shortcakes horizontally. Spoon the peaches and juice onto the bottoms, top with the cream mixture and replace the shortcake tops. Serve immediately.