Step 1

Preheat oven to 180C. Grease and line a 20cm-square cake pan with baking paper, allowing sides to overhang. Process beetroot in a food processor until finely chopped.

Step 2

Place beetroot, butter, brown sugar and dark chocolate in a saucepan over medium-low heat. Stir for 5 minutes or until melted. Transfer to a bowl. Stir in the egg. Combine flour, cocoa powder, nutmeg and cinnamon in a bowl. Sift flour mixture over chocolate mixture and stir to combine. Stir in walnuts. Pour into prepared pan. Bake for 30 minutes or until centre is just firm. Cool in pan. Cut into squares. Dust with icing sugar.