Batter: Cream together butter and sugar until smooth and creamy.
Add egg and vanilla.
Sift together dry ingredients and add to butter and sugar mixture 1/3 at a time, along with buttermilk.
Toss rhubarb with 1 tbsp flour and fold into batter.
Spoon batter into a greased 9 x 13 inch cake pan and smooth the surface.
Topping: Blend together topping ingredients and sprinkle evenly over batter. Last 3 ingredients, brown sugar, margarine and cinnamon.
Bake at 350F for 45 minutes or until cake has risen, browned and comes away from the edges, and skewer (or toothpick) inserted in the centre comes out clean
Last Step: Don't forget to share!
Make all your friends drool by posting a picture of your finished recipe on your favorite social
network. And don't forget to tag Just A Pinch and include #justapinchrecipes so we can see it too!