Start by preheating the oven to 400 degrees Fahrenheit (200 degrees Celsius). Then, line a baking sheet with parchment paper.
Next, whisk all of the dry ingredients together: the flour, sugar, lemon zest, baking powder, baking soda, and salt.
Now add the cubed butter into the dry ingredients. Cut the butter in with a pastry cutter or your fingers. Do this until the mixture is course and the crumbs are about the size of peas.
Next, whisk together the sourdough discard, buttermilk, and vanilla extract.
And then pour the wet ingredients into the dry ingredients and stir until combined. Add in the white chocolate chips. You want your dough to be workable but still a little sticky. Feel free to add more buttermilk (1/2 tbsp at a time) if the dough is too dry or add more flour (1 tbsp at a time) if the dough is too wet.
Turn the dough out onto a clean, lightly-floured work surface. Pat down the dough into a 6-7 inch circle that's about 1 inch thick. Cut into 8 triangles with a pizza cutter or knife. Then, spread the scones apart so that they have a few inches between each of them.
Optional but recommended: Chill the dough in the fridge for 15-30 minutes to help with texture and rise.
Next, brush the scones with buttermilk and sprinkle a little sugar on each (optional). Place the scones in the oven for about 20-22 minutes or until golden brown on top.
Let cool and enjoy your delicious white chocolate, lemon sourdough scones! :)