Preheat the oven to 400°
In the bowl of a mixer, place the flour and brown sugar, mix to combine.
Add in the baking powder, baking soda, and salt, and mix again to combine those ingredients.
Add the cold grated butter and mix to combine on low to medium speed.
Place the eggs, buttermilk, vanilla, and cinnamon if using it.
Add in the sliced banana, and mix on low, just until the banana incorperates.
When the dough begins to pull away from the sides of the bowl, stop mixing.
Turn the dough out onto your work surface, floured or on plastic wrap, and roll out 1 inch thick with a rolling pin. Cut into desired shape and size. 6-8 large scones, or many smaller scones.
I make the dough into a ball, then roll it into a dish shape and cut it with a sharp knife (not wiggling it- so the scones don't twist), then gently lift them with a spatula.
Place the scones on a parchment lined baking sheet, brush the tops of the scones with buttermilk.
Bake at 400° for 15 minutes.
Remove from oven and allow scones to cool for 5 minutes, serve warm or cooled. Slice and add butter, jam, or honey.