Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper to prevent sticking and for easy cleanup.

In a large mixing bowl, whisk together the flour, granulated sugar, light brown sugar, baking powder, and salt until well combined. This ensures all the leavening and seasoning are evenly distributed.

Add the cold, cubed butter to the dry ingredients. Using a pastry blender, two knives, or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining. The colder the butter, the flakier your scones will be!

Add the creamy peanut butter to the flour-butter mixture. Use your hands or a fork to work the peanut butter into the mixture until it's evenly distributed and crumbly. It should look like a wet sand texture.

In a separate small bowl, whisk together the cold whole milk and vanilla extract. Pour this wet mixture into the dry mixture. Gently mix with a fork or your hands until just combined and the dough starts to come together. Be careful not to overmix; the dough will still be a bit shaggy.

Add the semi-sweet chocolate chips to the dough. Gently fold them in until they are just distributed. Overmixing here will also develop gluten, making your scones tough.

Turn the dough out onto a lightly floured surface. Gently bring it together with your hands and pat it into an 8-inch round disc, about 1-inch thick. Use a sharp knife or a bench scraper to cut the disc into 8 wedges, like cutting a pie.

Carefully transfer the scone wedges to the prepared baking sheet, leaving a little space between each. In a small bowl, whisk the large egg with the water to create an egg wash. Brush the tops of the scones with this wash. Bake for 18-22 minutes, or until the tops are golden brown and a skewer inserted into the center comes out clean.

Let the scones cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely. This helps them firm up and prevents them from getting soggy.