Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
Mix dry ingredients: In a large bowl, whisk together the flour, sugar, baking powder, and salt.
Cut in the butter: Add the cold, cubed butter to the dry ingredients. Using a pastry cutter or your fingers, work the butter into the flour mixture until it resembles coarse crumbs. You want to see pea-sized pieces of butter throughout the dough — this is what makes scones flaky.
Mix wet ingredients: In a separate small bowl, whisk together the heavy cream (or buttermilk), egg, and vanilla extract (if using).
Combine: Slowly pour the wet ingredients into the dry mixture. Stir gently with a spatula or wooden spoon until the dough just starts to come together. If you’re adding fruit, chocolate, or nuts, fold them in now. Be careful not to overwork the dough.
Form the scones: Turn the dough out onto a lightly floured surface. Gently pat it into a 1-inch thick disc. Cut the dough into 8 wedges or use a round cookie cutter for traditional round scones.
Brush and bake: Transfer the scones to the prepared baking sheet. Brush the tops with a little extra cream to help them brown. Bake for 12-15 minutes, or until the scones are golden brown around the edges.
Cool and serve: Allow the scones to cool for a few minutes before serving with clotted cream, jam, or butter.