Rhubarb Custard Pie
["1 c. rhubarb, cut fine", "1 c. sugar", "1 Tbsp. flour", "1 c. milk", "2 egg yolks, beaten", "1/2 tsp. vanilla", "1 Tbsp. butter"]
["Combine all together.", "Pour in unbaked pie shell.", "Bake at 350\u00b0.", "Later cover with egg whites."]
["rhubarb", "sugar", "flour", "milk", "egg yolks", "vanilla", "butter"]