Preheat your oven to 350°F and line a baking sheet with parchment paper.
If making oat flour from scratch, blend rolled oats in a blender or food processor until fine.
In a bowl, mix oat flour with cold butter, baking powder, and brown sugar until crumbly. Add milk and mix until a thick dough forms.
Fold in chopped peaches and walnuts.
Shape the dough into a round scone and place it on the baking sheet.
Sprinkle with brown sugar and bake for 18-20 minutes until golden brown.
Let it cool, then enjoy your delicious scone!