Blueberry Surprise Cake
["2 c. blueberries", "3 Tbsp. shortening", "1/2 c. milk", "1 c. flour", "3/4 c. sugar", "1 tsp. baking powder", "1 c. boiling water", "1 Tbsp. lemon juice", "1 Tbsp. cornstarch", "1/4 c. sugar", "1/2 tsp. salt"]
["Sprinkle over batter.", "Pour 1 cup boiling water over top. Bake at 350\u00b0 for 50 to 60 minutes."]
["blueberries", "shortening", "milk", "flour", "sugar", "baking powder", "boiling water", "lemon juice", "cornstarch", "sugar", "salt"]