Line a large baking sheet with parchment paper or a silicone baking mat.
In a large bowl, whisk together flour, 1/4 c. sugar, baking powder, and salt.
Using a cheese grater, grate the butter into the flour mixture, and whisk or stir until the mixture resembles coarse crumbles. Alternatively, you could use a pastry blender or knife.
In a small bowl, whisk together 1/2 c. cream and the egg.
Add the egg mixture to the flour mixture, and stir until just combined. It should begin to form large clumps of dough.
Turn the dough out onto a lightly floured surface, and knead gently until dough comes together in a ball, about 6-8 times. Do not overmix.
Pat into a large disk, about 1-inch thick.
Using a star-shaped cookie cutter or biscuit cutter, cut 6-8 biscuits.
Arrange on the prepared baking sheet, about 2 inches apart.
Brush with cream and sprinkle evenly with turbinado sugar.
Bake at 425 degrees for 12-15 minutes, or until edges are golden brown.
Transfer to a wire rack to cool, about 10 minutes.