Prep. Preheat the oven to 425℉. Line a large baking sheet with a piece of parchment paper and set aside. Optional step: If your butter isn’t frozen, using a cheese grater, grate the butter, then place it on a plate and place it in the freezer for 5 minutes. Mix dry ingredients. In a large mixing bowl, add the flour, sugar, baking powder, baking soda, and salt. Using a whisk, stir to combine. If you’re making blueberry scones, this is where you would add the lemon zest. Add butter. Add the frozen grated butter to the bowl with the flour. Using a pastry cutter, cut the butter into the flour mixture. Set aside.
Mix liquids together. In a small bowl, add the milk and sourdough discard. Using a whisk, stir to combine.
Add liquids to the dough. Pour the milk and sourdough mixture onto the flour mixture. Using a spatula or wooden spoon, stir to combine as much of the mixture as you can.
Add mix-ins. Next, add the chocolate chips (if using). If you’re making blueberry scones, this is when you would add the blueberries.
Finish dough. Turn the dough out onto a clean, dry surface, gently folding the dough into itself to incorporate the remaining flour mixture and chocolate chips.
Gently shape and chill. Shape the dough into an oval and place it on a piece of parchment paper. Place it into the fridge for 8 minutes.
Cut. Remove the dough from the fridge. Using a knife or bench scraper, cut the dough into 12 triangles.
Place on baking sheet. Transfer the cut dough onto the parchment-lined baking sheet. If you’re making plain scones, brush the tops with some heavy cream and sprinkle with some sanding sugar. Bake. Bake at 425℉ for 18-20 minutes or until the scones are golden brown.