Preheat oven to 400*. Lightly grease a 9-inch square baking dish. In a sauce pan, mix brown sugar and cornstarch. Stir in rhubarb and water. Bring to a boil. Cook and stir 1 minute. Transfer to prepared baking dish. Dot with butter, and sprinkle with cinnamon. In a medium bowl, sift together flour, 1 tablespoon of sugar, baking powder and salt. Cut in butter until mixture resembles coarse crumbs. In a small bowl, mix the milk and egg. Add all at once to dry ingredients, stirring just to moisten. Kneed on floured board for 30 minutes, roll out and place on top of rhubarb mixture. sprinkle with granulated sugar and chopped nuts.

Bake for 25 minutes. Turn on broiler, and watch closely until nicely browned.