Toss together the rhubarb, quarter cup sugar, cornstarch, ginger, and cinnamon until well mixed. Set aside while making the batter.

Cream together the mayonnaise, sugar,  yogurt, and vanilla.

Stir in the prepared rhubarb, blending well.

Sift the flour and baking powder and soda together and fold into the rhubarb mixture. Stir just until evenly blended; do not overmix.

Generously oil a 7 X 11 inch pan. Pour in the batter and spread evenly.

With a fork, mix the butter, brown sugar, and spices until well blended. Add the flour and continue to mix just until large crumbs form. Using your fingers, distribute the crumbs evenly over the top, pressing them into the batter just slightly.

Bake at 350 (325 for a glass pan) for 30 to 35 minutes, until a toothpick inserted near the center comes out clean.