Rhubarb Upside Down Cake
["2 c. diced rhubarb", "1 egg", "7/8 c. sugar", "1 1/2 c. flour", "1 1/2 tsp. baking powder", "1 tsp. vanilla", "1/8 tsp. salt", "2/3 c. milk", "2 Tbsp. melted butter", "1 1/2 c. brown sugar"]
["Mix together egg, sugar, flour, baking powder, vanilla, salt and milk.", "Mix together in bottom of cast-iron skillet the 2 Tbsp. melted butter and brown sugar.", "Put about 2 cups rhubarb over mixture in skillet.", "Pour batter over rhubarb.", "Bake in 350\u00b0 oven for 30 to 45 minutes.", "Remove from oven, let sit a few minutes. Turn skillet upside down on cake plate.", "Cake will come right out."]
["rhubarb", "egg", "sugar", "flour", "baking powder", "vanilla", "salt", "milk", "butter", "brown sugar"]