Combine brown sugar, cold water, 2 tablespoon butter in saucepan. Bring to a boil. Cool. Sift flour, baking powder, salt, and cinnamon. Cream the rest of butter with flour mixture; add milk slowly.
Spread in an 8'x8' pan. Pour brown sugar mixture over batter, and sprinkle with chopped nuts. Bake at 350 degrees for 35-40 minutes. Serve warm with whipped cream.