Line a sheet tray with parchment paper, set aside. In a large bowl whisk together the flour, baking powder, baking soda, and salt.
Cut in the butter with a pastry cutter until the mixture resembles coarse crumbs, set aside.
Whisk together 1 cup of the buttermilk, brown sugar, and vanilla in a medium-sized bowl.
Pour the buttermilk mixture into the dry ingredients and stir until almost combined.
Add the chocolate chips and stir until combined. You may need to knead the dough some to get all of the chocolate chips incorporated.
On a lightly dusted clean work surface, work the dough into a ball. Flatten down the top and roll it out into an 8-inch circle.
Cut into 8 triangles.
Place the triangles on the sheet tray 2-3 inches apart. Place in the refrigerator for 15 minutes to rest.
Preheat the oven to 400°F.
Brush the tops with the remaining 1 tablespoon of buttermilk.
Top evenly with the sugar. Bake for 17-20 minutes until they start to turn golden brown on top.
Let cool slightly on the sheet tray and serve!