Heat the oven to 350ºF. Mix the flour, fructose, spices, baking soda, and salt in an unoiled 8 x 8 x 2-inch baking pan. Stir in the remaining ingredients, and bake for 35 to 40 minutes, until cooked through. Allow to cool on a wire rack before frosting.
Mix the apple juice concentrate, honey, lemon juice, and orange zest in a small saucepan, and bring to a boil. Let simmer for 5 minutes. Mix together the cornstarch and water, and stir into the saucepan. Simmer until the mixture thickens, stirring continuously. Blend this syrup and the tofu in a food processor until smooth. Frost the cooled cake.