Line a baking sheet with parchment. Whisk flour, sugar, baking powder, and salt in a large bowl. Keep the butter and cream cold.
Grate cold butter over the flour or cut it into small cubes. Work in lightly with a pastry blender until visible small flakes remain.
Whisk cream, egg, and vanilla separately. Pour into the flour mixture and stir with a fork until rough moist clumps form.
Turn onto a lightly floured surface and gather gently. Pat into an 8-inch circle about 1 inch thick without kneading smooth.
Cut into eight wedges with a sharp knife and move to the sheet, leaving 2 inches between them. Refrigerate 15 minutes while heating the oven to 400°F (200°C).
Brush tops with the separate tablespoon of cream and sprinkle optional coarse sugar. Avoid flooding the cut edges with liquid.
Bake 18–22 minutes until tops and bases are golden. A split edge should look set rather than wet or doughy.
Cool on a rack for 5–10 minutes and serve warm. Let remaining scones cool fully before enclosing them so trapped steam does not soften every surface.
