Step 1

Grease an 8-cup capacity bundt tin (mine is 23cm in diameter) with melted butter and dust with flour, shaking off the excess. Refrigerate while you prepare the batter to allow the butter to harden.

Step 2

In a stand mixer or using hand-held beaters, cream butter and sugars until pale. Add eggs one at a time, mixing well between each addition. Add rum and beat well. Sift together flour, bicarb and cinnamon and add to the bowl in two batches with the buttermilk, mixing until just combined. Fold through walnuts.

Step 3

Spoon mixture into prepared bundt tin and smooth the top. Bake for 40-45 minutes until a skewer inserted into the centre comes out clean. Allow to cool slightly in the tin then turn out onto a rack to cool completely.

Step 4

Whip cream with extra sugar until thick. Dollop quenelles of cream at intervals around the cake and garnish with extra chopped walnuts.