John Whaite's bundt cake recipe

Ingredients

• 250 g salted butter, softened
• 400 g light muscovado sugar
• 1 orange, zest only
• 2 large eggs
• 300 ml buttermilk
• 300 g plain flour
• 2 tsp baking powder
• 3 tsp ground mixed spice
• 100 g pecans, roughly chopped
• 100 g walnuts, roughly chopped
• 200 g best quality mincemeat
• 100 g marzipan, cut into small cubes
• 1 scattering icing sugar, to dust