Preheat oven to 400 degrees. Line two baking sheets with parchment paper (or a Silpat mat), and set aside.
Sift all purpose flour, sugar, cinnamon, baking powder, and salt into medium bowl. Add chilled margarine (or butter); using fingertips (or a pastry cutter), until mixture has a coarse consistency.
In another mixing bowl, whisk together buttermilk, egg, and vanilla. Add in the mashed bananas.
Gradually add the wet ingredients into the dry ingredients tossing with a fork until dough comes together in moist clumps. If dough seems to be too dry add a little more buttermilk by the teaspoonful.
Drop dough by 1/4 cupfuls (I used a regular sized ice-cream scooper) into large rimmed baking sheet, spacing apart. (Line them up 6 per sheet). Sprinkle with a bit of cinnamon sugar.
Bake scones until golden brown and tester inserted into center comes out clean, about 15-18 minutes (baking time could vary depending on the size of your scones that you scooped out so check on them at about 15 minutes if you made them smaller. Mine were ready at 18 minutes).
Serve warm or at room temperature.