Cake
Heat the oven to 180C/350F. Mix the flour, brown sugar, allspice, baking soda and salt in an un-oiled 20 x 20 x 5 centimeter (8 x 8 x 2 inch) baking pan. Stir in remaining cake ingredients and bake for 30-40 minutes until cooked through. Allow to cool on a wire rack before frosting.
Icing
Mix the apple juice concentrate, maple syrup, cider vinegar and orange zest in a small saucepan and bring to the 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 together in a food processor until smooth. Frost the cooled cake.