Preheat the oven to 400 degrees, and prepare a sheet pan with a silpat or parchment paper.
In the bowl of a food processor, combine the dry ingredients. Add in the cold butter and pulse until crumbly. (Butter pieces should be pea-sized)
In a glass measuring cup combine the buttermilk, banana and egg and mix them together well with a fork. Add the wet ingredients to the dry ingredients and pulse in short bursts until the dough comes together.
Turn dough out onto a floured surface and gently form into two equal discs. Spread the cinnamon mixture onto one disk, and place the other on top.
Carefully cut the dough into wedges and transfer to cookie sheet.
Bake the scones at 400 degrees for 10-12 minutes. Enjoy warm.
For filling:
Stir together the melted butter, brown sugar and cinnamon in a small bowl.