1 1/2 c. brown sugar
1 c. buttermilk
1 tsp. baking soda
1/3 c. brown sugar
1 egg
2 c. flour
1 1/2 c. rhubarb, diced finely
1 tsp. cinnamon

Preheat oven to 350 degrees. Mix in order the brown sugar, egg, buttermilk, flour, soda, and rhubarb. Place in a greased and floured 9 x 13 inch pan. Mix the 1/3 cup brown sugar and cinnamon together. Sprinkle on the top of the cake. Bake 45 minutes.