Place chopped nectarine in a freezer safe tray or bowl. Cover and let chill in the freezer for 15-20 minutes until semi-solid.
In a large bowl, whisk together flour, baking powder, baking soda, salt, brown sugar. Toss in cubed butter. Cover and let chill in the freezer for 15 minutes until ingredients are cold.
Preheat oven to 400℉. Line baking sheet with parchment paper or silicon baking mat. Set aside.
Remove flour mixture from freezer. Using a pastry blender (pastry cutter) or two forks, cut butter into flour until mixture resembles coarse sand. In a small bowl, whisk together milk, cream, extracts, and egg until well combined. Add wet ingredients to flour mixture. Fold to combine until mixture is a "shaggy mess." Gently fold in cold nectarines.
Dump coarse dough onto a floured work surface. Gently knead dough together. Pat dough into a rectangle with a thickness of about 1-inch. (Alternatively, shape into an 8-inch circle.) Cut scones into 8 pieces.
Transfer scones onto prepared baking sheet, allowing at least 2-inches of space between scones. Lightly brush scone tops with heavy cream and sprinkle with turbinado sugar.
Bake for 23-25 minutes until scones have puffed up and the tops are golden brown in color. Let scones cool slightly on baking sheet before transferring to a wire rack to cool. Serve scones warm or at room temperature.