Royal Rhubarb Cake

2 1/3 cups flour
1 tsp Salt
1 tsp baking soda
1 1/2 cups brown sugar, firmly packed
1/4 cup soft butter
1 cup sour cream
1 egg, beaten
1 tsp vanilla
4 cups rhubarb, cut in 1/2 inch pieces
3/4 cup sugar
1 tsp cinnamon

In a large mixing bowl, stir together flour, salt and soda.  Add brown sugar, butter, sour cream, egg and vanilla.  Beat until well mixed.  Fold in rhubarb.  Turn into a buttered 9 x 13 pan.  Combine white sugar and cinnamon and sprinkle over the top.  Bake in a preheated 350 degree oven for 50-55 minutes or until done.  Cool in pan.  Serve warm topped with whipped cream.