Makes 12

31/2 cups self-rising flour*

1/4 cup granulated sugar

3/4 cup cold unsalted butter, cubed

3/4 cup cold whole buttermilk

1/2 cup mashed strawberries

1 large egg, beaten Turbinado sugar

Strawberry jam and sweetened whipped cream, to serve

Preheat oven to 425°. Line a baking sheet with parchment paper.
In a large bowl, stir together flour and granulated sugar. Using two forks or a pastry blender, cut in cold butter until mixture is crumbly. Stir in cold buttermilk and strawberries until a shaggy dough forms.
Turn out dough onto a lightly floured surface. Pat dough into a rectangle, and cut into fourths. Stack each fourth on top of each other, and pat down into a rectangle again. Repeat process 3 more times.
Pat or roll dough 1 inch thick. Using a 21/2-inch round cutter dipped in flour, cut dough without twisting cutter, rerolling scraps as necessary. Place biscuits 2 inches apart on prepared pan. Freeze until cold, about 10 minutes. Brush with egg; sprinkle with turbinado sugar.
Bake until golden brown, about 15 minutes. Serve with jam and whipped cream, if desired.