Cream together 1 1/2 cups brown sugar and 1/2 cup butter. Then beat in 1 egg. Then add 1 cup buttermilk and 1 teaspoon vanilla. Then sift and add 1 teaspoon baking soda, 1/2 teaspoon salt and 2 cups flour. Then add 1 1/2 to 2 cups rhubarb. Pour into 9 x 13-inch greased pan.

TOPPING:

Mix 1/4 cup white sugar, 1 teaspoon cinnamon and 1/2 cup chopped nuts. Sprinkle over unbaked cake. Bake at 350 degrees for 40 to 45 minutes.