Preheat oven to 170°C. Grease a 22cm springform pan and line base and sides with baking paper.

Using an electric mixer with whisk attachment, beat the oil, sugar, eggs and vanilla until thick. Stir in chopped nuts, meal, zucchini and spices. Sift over soda and flours, and stir to combine. Pour into pan and bake for 70 minutes or until a skewer inserted in centre comes out clean. Cool in pan for 20 minutes, then turn onto a wire rack and cool completely.

For frosting, use electric beaters to beat the butter and sugar until light and fluffy. With motor running, gradually add cheese, beating well between additions. Add zest and juice and beat until smooth.

Using a bread knife, slice the cake into two rounds and set aside top. Spread a third of the frosting over the bottom half, then replace top and spread cake with remaining frosting. Decorate with slivered pistachios.