Whisk flour, brown sugar, baking powder, salt, and cinnamon in a medium to large bowl. Place the bowl in the refrigerator or freezer to keep cold.
Grate frozen butter and add to the flour mixture. Use a pastry cutter or fork to combine until it looks like a coarse meal.
If adding chocolate chips or nuts, gently fold into flour/butter mixture.
Whisk heavy cream, mashed bananas and vanilla extract together and add to flour mixture. Use a spatula to bring the dough together until it starts to form large clumps and still has crumbly flour bits.
Dump the dough onto a piece of parchment paper and use your hands to lightly bring the dough together and nudge into an 8” circle. You don’t want to knead the dough, just bring it together so it’s cohesive.
Cut into 8 equal scones.
Brush tops of scones with more heavy cream (approximately 1-2 tablespoons) and sprinkle with turbinado sugar, if using.
Place prepared scones in the freezer while the oven preheats to 400°F.
Separate and bake on a parchment lined baking sheet for 20-25 minutes, until lightly golden.
Make glaze while scones cool. Stir together the powdered sugar, mashed banana, vanilla and heavy cream until well incorporated.
Drizzle glaze over cooled scones and enjoy.