2 cups all-purpose flour
2 teaspoons baking powder
1 teaspoon baking soda
1 teaspoon salt
1 cup butter, softened
1 egg
1 cup white sugar
2 tablespoons orange juice concentrate
1/4 cup orange juice concentrate
In a large bowl, mix flour, baking powder, baking soda and salt. Mix well. Strain dough into a greased and floured 9 inch springform pan. Form into a rectangle. Spread filling on top of crust. Cover and refrigerate at least 4 hours.
Preheat oven to 375 degrees F (190 degrees C). Cut between two baking sheets to fit inside crust. Spread icing over filling with a silver spoon. Serve at room temperature, or refrigerate 8 hours or overnight.