Preheat oven to 400ºF.
In a large mixing bowl, combine flour, ½ cup sugar, baking powder, baking soda, and cinnamon.
Next, add rhubarb and mix again.
Slow add heavy whipping cream while continuing to stir. Dough will come together as you work it. I prefer to use my hands.
Place dough on a greased baking sheet. Wet your hands and gently form it into a 10-inch circle that is about ¾-inch thick.
Sprinkle 1 tablespoon of sugar
Slice dough into 8 wedges and split them apart so they are not touching.
Bake for 20-25 minutes or until baked through and bottoms are golden brown. (Do not overcook. This will cause your scones to dry out.) Allow to cool on wire rack.
Prepare glaze by whisking powdered sugar, heavy whipping cream, and vanilla. (If glaze is a bit too thick, add a little heavy whipping cream. If glaze is too thin, add a little powdered sugar.)
Drizzle glaze over scones and serve.