01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - Whisk flour, sugar, baking powder, salt, and cinnamon in a large bowl.
03 - Add cold butter and cut in using a pastry blender or fingertips until the mixture resembles coarse crumbs.
04 - Whisk mashed banana, heavy cream, egg, and vanilla extract together in a separate bowl.
05 - Pour wet ingredients into dry mixture and stir gently until just combined. Do not overmix.
06 - Turn dough onto a lightly floured surface. Pat into a 7-inch disc about 1-inch thick. Cut into 8 wedges and arrange on prepared baking sheet, spaced apart.
07 - In a small bowl, mix flour, brown sugar, cinnamon, melted butter, and pinch of salt until crumbly. Sprinkle streusel evenly over scones.
08 - Lightly brush tops of scones with extra heavy cream.
09 - Bake for 20 to 22 minutes, until golden brown and a toothpick inserted in the center comes out clean. Cool on a wire rack.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth. Drizzle glaze over cooled scones.
11 - Serve scones warm or at room temperature.