Preheat the oven to 170°C fan and make sure your bundt tin is very well greased.
Cream the butter, sugar and orange zest until very well combined and the sugar has more or less dissolved into the butter. Beat in the eggs and buttermilk, then sift over the flour, baking powder and mixed spice and fold in.
Fold in the nuts, mincemeat and marzipan, then scoop into the prepared tin, level off and bake for 60-75 minutes or until a skewer comes out clean.
Remove from the oven and allow to cool completely in the tin. To serve sift over some icing sugar, and serve. This is gorgeous served with a cheese board!