Fruit Topping:
Melt Butter in bottom of 9-inch square pan. Stir in 1/4 cup brown sugar.. Arrange orange slices on the mixture. Heat blueberries until juicy. Combine remaining 1/4 cup brown sugar with the cornstarch and add to hot blueberries. Cook over medium heat, stiring constantly, until clear and thick, about three minutes. Spread over orange slices.

Cake:
Cream butter, sugar and vanilla until light and fluffy. Beat in egg. Sift together flour and baking powder. Add alternately with milk, beginning and ending with flour. Stir in grated orange peel. Spoon batter over toppin mixture in pan. Bake at 375 degrees for 30 to 35 minutes. Turn upside down on serving platter. Serve warm or cold with whipped cream or ice cream

Penuche Icing:
Combing butter or margarine, milk and brown sugar in small saucepan. Cook and stir for 3 minutes after it begins to simmer. Cool. Add connfectioner's sugar and vanilla; beat until smooth. Adjust consistency by adding (carefully!) more milk or confectioner's sugar