Blueberry Upside Down Cake
["6 tbsp. Butter, soft and divided", "2 c. fresh Blueberries", "3/4 c. Sugar", "1 Egg", "1 tsp. Vanilla", "1/2 c. Milk", "1/3 c. packed Brown Sugar", "1 1/4 c. Cake Flour", "1 1/2 tsp. Baking Powder", "Whipped Topping (optional)"]
["In a small saucepan, melt 2 tbsp. butter; stir in brown sugar.", "Spread in ungreased 8 in. baking dish.", "Arrange blueberries in a single layer over brown sugar mixture.", "Set aside.", "In a large mixing bowl cream remaining ingredients and beat in sugar.", "Add egg and vanilla.", "Mix well. Combine flour and baking powder.", "Add to creamed mixture alternately with milk. Carefully pour over blueberries.", "Bake at 350 degrees for 40 to 50 minutes or until a toothpick inserted near center comes out clean. Immediately invert on a serving platter. Serve with whipped topping if desired."]
["Butter", "fresh Blueberries", "Sugar", "Egg", "Vanilla", "Milk", "Brown Sugar", "Flour", "Baking Powder", "Topping"]