Preheat oven to 375°F.
In a medium bowl, measure flour, sugar, baking powder, and salt.
Add butter and use either a pastry blender, a fork or your fingers to break the butter into small pea-size pieces.
Measure and whisk milk, egg and vanilla into a small bowl. Then slowly add to the flour mixture, including rhubarb,then mix together until combined. The dough should be moist. Option is to mix in an electric mixer, but make sure you don't over mix.
Using an ice cream scoop, take a generous scoop of the dough and place on a baking sheet lined with parchment paper, spacing them about 1 inch apart.
Bake for about 25-30 minutes or until the edges are a light golden brown. Cool on a cooling rack before serving.
Lemon Glaze: Whip together the powdered sugar, milk, and lemon. Drizzle over scones and serve.
