Mix together flour and sugar, cut in butter until crumbly. Pat into 9 x 13 pan. Bake at 350 for 10 minutes. Cover with rhubarb.
Mix filling ingredients together and pour over rhubarb. Bake for 45 minutes.
Beat together meringue – 6 egg whites, 3/4 cup sugar and 1 tsp vanilla mixture until stiff. Spread on cake and bake 15 minutes until browned.