Ingredients
Filling
3 cups sliced rhubarb, (1 inch pieces) fresh or frozen
2 pints fresh strawberries, mashed
2 tablespoons lemon juice
1 cup sugar
1/3 cup cornstarch
Cake
3 cups all-purpose flour
1 cup sugar
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1 cup butter, cut in small pieces
1 1/2 cups buttermilk
2 eggs
1 teaspoon vanilla extract
Topping
1/4 cup butter or margarine
1/4 cup all-purpose flour
3/4 cup sugar
Instructions
Generously butter a 9 x 13 inch baking dish and have ready a cookie sheet or jelly roll pan (or tin foil on the baking rack) to place under the baking dish to allow for any fruit bubbling over. Preheat oven to 350*F.
In a large saucepan, combine the rhubarb, strawberries, and lemon juice. Cook for 5 minutes over medium heat. Combine the sugar with the cornstarch and add to the fruit mixture. Bring to a boil over medium heat and cook for about 5 minutes, stirring constantly, until the mixture is thickened, and the cornstarch mixture looks clear. Remove from heat.
In a large bowl combine flour, sugar, baking powder, baking soda, and salt. Cut the butter in with a pastry blender, or use your fingers to rub the butter into the dry ingredients, until you have a mixture that resembles coarse crumbs. In a separate bowl beat together the eggs, buttermilk, and vanilla. Add to the dry ingredients and mix to combine.
Spread half of the batter mixture into the prepared 9 x 13 inch baking pan. Top with the strawberry rhubarb mixture, carefully spreading as necessary. Using a tablespoon, drop the remaining batter onto the filling.
For the topping, melt the butter either in your microwave or in a small saucepan over low heat. Add the flour and sugar and mix until the mixture is crumbly. Sprinkle over batter.
Place baking dish on the baking sheet and bake for approximately 45 minutes or until the cake is done. A toothpick inserted into the center of the batter will probably have the fruit mixture cling to the toothpick, but you are looking to see that the batter is cooked.
Cool cake on rack. Cut in squares to serve. Will easily make 12 squares.
Notes: This may be sacrilege, but I preferred this cake slightly warm and the filling all sweet, gooey, and oozy.