Whisk flour, sugar, baking powder, and salt together in a large bowl.
Work in the butter with a fork or your fingers until resembles a coarse meal.
Toss in your add-ins.
Whisk buttermilk, egg, and vanilla.
Pour the wet into the dry ingredients and stir with a rubber spatula just until combined.
Place the dough onto the counter and shape it into a ball.
Cut the dough into 8-10 wedges.
Transfer onto a parchment paper-lined baking sheet and chill in the fridge for 20 minutes.
Brush the surface with buttermilk and bake in a 400F oven for 20 minutes.