For sauce: In a saucepan, combine sugar, flour, cinnamon and salt. Stir in water; add butter. Bring to a boil; cook and stir for 1 minute. Remove from heat. Add vanilla and if desired, enough food coloring to tint sauce a deep pink; set aside.
To make dough, combine flour, sugar, baking powder and salt. Cut in butter until mixture resembles coarse crumbs. Add milk and mix quickly. Do not over mix. Gather dough in a ball and roll out onto a floured surface into a 9x12” rectangle.
For filling: spread dough with softened butter; arrange rhubarb on top. Combine sugar and cinnamon; sprinkle over rhubarb.
Arrange slices cut side up in a greased 9x13” baking dish. Pour sauce over.
Bake at 350 degrees for 35 to 40 minutes, or until golden brown. Yield: 12 servings.