Preheat oven to 400°F (204°C). Line a baking tray with parchment paper.
In a large bowl, whisk together flour, sugar, baking powder, and salt.
Add grated, frozen butter. Toss until the mixture resembles coarse crumbs.
In a separate bowl, whisk together sourdough discard, cream, and vanilla.
Add wet ingredients to dry and fold gently with a rubber spatula until combined.
Add your mix-ins and fold just until evenly distributed.
Turn dough onto a lightly floured surface. Pat into a 1-inch thick circle.
Cut into 6 wedges or rounds and transfer to prepared tray.
Chill scones for 30 minutes for best results.
Brush tops with cream and sprinkle with coarse sugar.
Bake for 18–22 minutes, or until golden brown and fully baked.
Cool on a wire rack before serving or glazing.