1. Preheat the oven to 400 F and line a large baking sheet with parchment paper or a silicone baking mat.
2. In a medium sized bowl, whisk together the flour, baking powder, baking soda and salt. Cut in the cold butter using a fork or a pastry blender until the mixture resembles coarse pea-sized crumbs.
3. In another mixing bowl, whisk the sugar together with the egg until combined, then add the heavy cream. Pour the liquid ingredients into the dry, and gently begin to combine together with a spatula. Add the grapefruit juice and zest, and use the spatula to mix gently until a soft dough is formed. Do not overmix!
4. Transfer the dough to a lightly floured surface, and using floured hands, form the dough into an 8″ disc and cut into 8 wedges. Place each wedge on the prepared baking sheet a couple inches apart. Bake the scones for 18-20 minutes, until the scones are light brown around the edges. Allow the scones to cool for a few moments before adding the glaze.
5. Make the glaze. While the scones are baking, prepare the glaze by combining the powdered sugar, grapefruit juice and zest. Add more juice or more sugar to achieve the consistency you’d like. Drizzle the glaze over the fresh scones before serving.

Scones are best enjoyed immediately, but will keep at room temperature in an airtight container for 2-3 days. I like to re-heat my leftover scones and add some butter 🙂