Begin by pre-heating your oven to 180C/gas mark 4.
Grease your doughnut pan with a little butter and place to one side.
Whisk together the pumpkin puree,, brown sugar, milk, egg and butter on a high speed until light and airy.
Fold in the flour and spices until just incorporated (you don't want to overwork the mix).
Carefully spoon the mixture into the pans (or pipe if easier).
Bake in the centre of the oven for 12-15 minutes or until they are springy to the touch and golden.
Leave the doughnuts to cool in the pan for a few minutes before turning them out on to a cooling rack. (If they aren't coming out very easily, run a spatula around the edges of each doughnut to loosen them).
Once cool, mix together the icing and cardamom milk.
Using a teaspoon, drizzle the icing over the doughnuts.
Finish with a sprinkling of chopped nuts if desired.