FILLING:

3 c. sliced fresh or frozen rhubarb, cut in 1 inch pieces
1 qt. fresh strawberries, mashed
2 tbsp. lemon juice
1/3 c. cornstarch
1 c. sugar

CAKE:

3 c. all-purpose flour
1 tsp. baking powder
1/2 tsp. salt
1 c. butter, cut in pieces
1 1/2 c. buttermilk
1 c. sugar
1 tsp. baking soda
2 eggs
1 tsp. vanilla

TOPPING:

1/4 c. butter
3/4 c. flour
3/4 c. sugar

In a large saucepan combine rhubarb, strawberries and lemon juice. Cover and cook over medium heat for about 5 minutes. Combine sugar and cornstarch; stir into saucepan. Bring to a boil, stirring constantly until thickened. Remove from heat and set aside.

In a large bowl, combine flour, sugar, baking powder, baking soda and salt. Cut in butter until mixture resembles coarse crumbs. Beat buttermilk, eggs and vanilla. Stir into crumb mix. Spread half of the batter evenly into a greased 13x9x2 baking dish. Carefully spread filling on top. Drop remaining batter by tablespoon over filling.

For topping, melt butter in a saucepan over low heat. Remove from heat and stir in flour and sugar until mixture resembles coarse crumbs. Sprinkle over batter. Bake at 350 for 40-45 minutes. Cool in pan and cut in squares.