Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper and set aside.
In a large bowl whisk together the flour, granulated sugar, baking powder, and a pinch of salt (if using).
Cut the cold butter into the dry ingredients using a pastry cutter, two forks, or your fingers until the mixture resembles coarse sand with some pea-sized butter pieces remaining.
In a small bowl whisk the egg, 1/3 cup peanut butter, sour cream, and vanilla until smooth.
Pour the wet mixture into the dry ingredients and fold gently with a spatula until just combined; add extra sour cream 1 tablespoon at a time only if the dough is too crumbly to hold together.
Fold in the mini chocolate chips until evenly distributed.
Turn the dough onto a lightly floured surface and pat into an 8-inch round about 2 inches high.
Using a large knife, cut the round into 8 equal wedges and transfer the wedges to the prepared baking sheet, spacing them about 2 inches apart.
Bake for 12–15 minutes, or until the scones are very lightly golden and a toothpick inserted comes out clean or with a few moist crumbs; avoid overbaking.
Cool the scones on the baking sheet for about 5 minutes, then transfer to a wire rack to finish cooling while you prepare the glaze.
For the glaze, warm 1/2 cup peanut butter in a microwave-safe bowl for 30 seconds to soften, then whisk in the confectioners' sugar and 2 tablespoons milk or cream until smooth; add more milk or sugar to reach desired consistency.
Drizzle or spread the glaze over cooled scones and allow it to set before serving.