3/4 c. white sugar
3/4 c. brown sugar
1/2 c. softened butter
1 egg
1 tsp. vanilla
1 c. buttermilk (or 1 c. sweet milk with 1 tbsp. lemon juice)
2 c. flour
1 tsp. baking soda
2 to 2 1/2 c. finely chopped rhubarb

TOPPING:

1/3 c. sugar
1 1/2 tsp. cinnamon
1 c. walnuts, chopped

Cream butter and sugar. Add egg and vanilla. Mix together dry ingredients. Alternate adding dry ingredients and buttermilk into creamed mixture. Pour into greased 9 x 13 inch cake pan. Combine topping ingredients and sprinkle on cake. Bake at 350 degrees for 35 to 40 minutes.