Preheat the oven to 400 degrees. and position the rack in the center. Line a baking sheet with parchment paper.

In a large bowl, whisk together the flour, brown sugar, baking soda, baking powder, salt and oats. Add the butter and use your fingertips (or a pastry cutter) to rub (or cut) the butter into the flour mixture until the butter is pea-size and the mixture looks like chunky coarse sand.

In a small bowl, whisk together the buttermilk and egg yolk until combined.

Make a well in the dry ingredients and pour the buttermilk mixture into the center of the well. Add the peanut butter. Gently mix and knead the dough in the bowl until it starts to come together. Add the chocolate chips and knead until just incorporated. It’s important to not overwork the dough.

Turn the dough out directly onto the prepared baking pan and shape it into a disk 7 1/2 to 8 inches in diameter and about 1 1/2 inches high. Beat the egg white slightly, brush the top of the dough with the egg white, and sprinkle with the raw sugar, if you wish.

Cut the dough into 8 weges- but do not separate the wedges- and bake for 18 to 22 minutes, or until the scones start to brown, rotating the baking sheet halfway through. You can also check for doneness by inserting a toothpick into the center of the scones. The toothpick should come out clean or with just a few crumbs. Make sure the scones are fully cooked!

Remove from the oven, let cool for 5 minutes and re-slice and separate the scones. Serve slightly warm or transfer to a wire rack to cool completely. Scones taste best when consumed within 24 hours of baking, but you could store them in an air-tight container for up to 2 days.