Combine the flour, baking powder, sugar and salt, in a large bowl. Stir until they are very well combined.
Grate the butter into the flour mixture and stir until the butter is well incorporated and no large lumps remain.
Add the chocolate chunks to the flour mixture and stir to combine.
Whisk together the sourdough discard, milk, eggs, and vanilla extract in a separate bowl.
Pour the wet discard mixture into the bowl with the flour mixture and chocolate chunks. Stir everything together until it forms a cohesive ball of dough, with no dry flour remaining on the bottom of the bowl. If the dough is too dry to come together into a single ball of dough, add a splash more milk (1 Tbsp or so) until it comes together.
Form a dough ball at the bottom of your mixing bowl and cover with plastic wrap. Allow your scone dough to proof for 1-3 hours, until your dough ball noticeably grows in size, at least by a quarter the volume, ideally the volume will double. (Yes, this step takes a little extra patience, but the fluffy texture from the sourdough makes these scones a little extra special! You could also bake this right away, they just won’t be as fluffy and will be more like a classic scone.)
Press the dough out into an 8-inch diameter circle on a piece of parchment paper. Cut the circle into 6 wedges. (To stretch this recipe further, you could cut into 8 wedges.) Place the cut scones on a parchment lined baking sheet.
Bake the scones in the preheated 425ºF oven for 15-17 minutes, or until they are golden brown. Transfer the baked scones to a wire rack to cool.
While the scones are cooling, combine powdered sugar with 1 Tbsp milk until it forms a thick glaze. Drizzle the glaze over the cooled scones, then enjoy!
*I put a stick of butter into the freezer 5-10 minutes before I start baking to make it easier to grate. You want it to be cold and stiff, not frozen solid; otherwise, it'll be too hard to grate.**You could use chocolate chips, but I find scones to be too bready without the larger pockets of chocolate created by using chunks.***I use the discard from my 100% hydration starter. If you do not have any sourdough discard, you can make this scone recipe with 2 cups of flour instead, skipping the discard ingredient, and there's no need to proof the dough for 1-3 hours.