Mix together cinnamon, walnuts and 1/2 cup sugar in a small bowl and set aside.
In another bowl, thoroughly blend the flours, starches, 3/4 cup sugar, baking powder, baking soda and salt.
In another bowl combine orange juice, lemon juice, zest, eggs, and oil. Beat till well blended. Then add into the flour mix and blend well.
Pour half of batter into a greased 8 x 8 inch pan. Sprinkle half the cinnamon sugar mix on top of it. Pour over the remaining batter on top then finish it off with another sprinkling of the sugar/cinnamon mixture.
Bake at 350°F for 30-35 minutes or until lightly browned.