Preheat the oven to 190˚C / fan oven 170˚C / Gas Mark 5 and lightly grease two baking sheets. Place the butter, Demerara Sugar and Light Muscovado Sugar in a large Mason Cash mixing bowl then beat together with a wooden spoon until smooth and creamy. Add the egg, carrot and oats then beat again until nicely incorporated.
Sift over the flour, bicarbonate of soda and mixed spice then beat together with the wooden spoon until completely incorporated. Place heaped teaspoons of the mixture onto the prepared baking sheets, flattening them down slightly and bake for 10 - 12 minutes until lightly golden. Allow to cool on the tin for 5 minutes before transferring to a wire rack.
To decorate, combine the icing sugar, zest and just enough orange juice to make an icing with a nice drizzling consistency. Drizzle over the cookies, then scatter with the chopped walnuts and finish with a sprinkling of cinnamon. Allow to set before serving.
These cookies will keep well in an airtight container for a couple of days.
Do you like how the tangy orange compliments the spiced biscuits?