• Prepare a baking sheet by lining it with parchment paper and set aside.
• In a large bowl, whisk together all-purpose flour, granulated sugar, baking powder, baking soda, salt, poppyseeds, and half of the lemon zest.
• Using a pastry cutter or your fingers, work the cold butter into the flour mixture until pea-sized crumbs form.
• In a separate bowl, whisk together sourdough discard, heavy cream, and vanilla extract.
• Gently stir the wet ingredients into the dry ingredients until just combined. Turn the dough onto a lightly floured surface and bring it together with your hands.
• Pat the dough into a 6 to 7-inch round, about 1 inch thick. Cut into 8 wedges and transfer to the prepared baking sheet.
• Place the scones in the refrigerator for 15 to 20 minutes while preheating the oven to 400 degrees Fahrenheit (200 degrees Celsius). This helps with flakiness.
• Bake for 18 to 22 minutes, until golden brown and baked through. Cool on a wire rack.

Make the Lemon Glaze

• Whisk powdered sugar and lemon juice until smooth and thin enough to drizzle. Adjust the thickness of the glaze to your liking.

Optional Zested Sugar Topping

• Rub the remaining lemon zest into the granulated sugar with your fingers until fragrant.
• Drizzle the top of the scones with thin lemon glaze and sprinkle with zested sugar while the glaze is still wet.