2 tablespoons butter
8 eggs
1 tablespoon brown sugar
1/4 cup white sugar
1/2 teaspoon salt
1/8 teaspoon lemon zest
2 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
1 cup sliced marshmallows
1 cup frozen blueberries, thawed
Heat oven to 350 degrees F (175 degrees C).
In a large bowl, cream together the butter or margarine, eggs, brown sugar, white sugar, salt, lemon juice and orange zest. Set aside.
In a separate bowl, stir together flour, baking powder, baking soda and marshmallows. Fold into butter mixture.
Arrange marshmallows in bottom of 9-inch prepared pan. Pour batter over marshmallows.
SPREAD remaining batter over marshmallows in pan. Cover pan with parchment/ foil. Brush tops of marshmallows with egg white to just moisten. Sprinkle blueberries over marshmallows.
Bake 25 to 30 minutes in center position; allow to cool on baking sheet for several minutes before removing foil. In melted margarine, beat blueberries on medium--high speed until mixture is thick. Let cool to room temperature. 3 to 4 minutes before serving.