Rhubarb Upside-Down Cake
["5 c. rhubarb, cut in small pieces", "4 c. small marshmallows", "1 c. sugar", "1 3/4 c. flour", "2 tsp. baking powder", "1/4 tsp. salt", "1/2 c. butter", "1 c. sugar", "3 eggs, separated", "1/2 c. milk", "1/2 tsp. vanilla"]
["Mix rhubarb, marshmallows and 1 cup sugar. Spread in bottom of sheet cake pan.", "Sift flour, baking powder and salt. Cream butter and 3/4 cup sugar until fluffy. Add well beaten egg yolks. Beat well. Add flour mixture, alternating with milk, beating after each addition. Add vanilla. Beat egg whites until just stiff and gradually beat in rest of sugar. Fold lightly but thoroughly into batter.", "Pour over rhubarb. Bake at 350\u00b0 about 35 minutes. Serve warm with whipped cream."]
["rhubarb", "marshmallows", "sugar", "flour", "baking powder", "salt", "butter", "sugar", "eggs", "milk", "vanilla"]