In a bowl, combine flour, sugar, baking powder and salt. Stir in blueberries and orange zest. In another bowl, beat eggs; add milk and oil. Stir into dry ingredients just until moistened. Pour into a greased 9x5-in. loaf pan. Bake at 350° for 1 hour or until a toothpick inserted in the center comes out clean. Cool in pan for 10 minutes; remove to a wire rack to cool completely. Serve with cream cheese if desired.