Ingredients
150g light muscovado sugar 
150g dark muscovado sugar - here if you don’t have both you can just use light or dark 
300g self-raising flour 
2 tsp bicarbonate of soda 
½ tsp ground cardamom 
3 tsp mixed spice 
175g mixed nuts, roughly chopped (I like my nuts to be cut roughly so some are small and some are larger.  I also like to use a combination of pistachios, pecans, walnuts or almonds but really as long as they are not salted, use whatever you have or like) 
500g pumpkin/squash *
4 eggs 
200g melted butter 
2 oranges, zest and juice 
85g soft butter 
200g mascarpone  
120g icing sugar, sieved 
4 tsp orange liqueur 
 

* This equates to roughly half a squash or, if you are carving your pumpkin, will probably be around the amount of flesh you take out.

Method
Heat the oven to 180c and butter and line a square or rectangle cake tin with butter and baking parchment/grease proof paper. 

In a fairly large bowl put your sugars and the flour and if there are any large sugar clumps, just crush them, either with your hands or with your wooden spoon.  Add to the bowl the bicarb, cardamom and mixed spice and mix together.  Add the nuts, squash and orange zest and mix again.  Put the eggs, melted butter and ¾ of the orange juice in a jug and mix.  Add to the bowl and mix until combined. 

Pour the cake mixture into the prepared tin and put into the oven.  My tin is 23cm square and took 1 hour 15 minutes to bake, I have used a tin that larger and that took only 50 minutes so my suggestion here is to check at 45 minutes and then every 10 minutes thereafter until your cake is cooked. 

Mix together your orange juice and liqueur and when your cake comes out of the oven poke the cake all over the top.  You want to poke it through almost to the bottom.  Reserve 1½ tsp of the orange.  With the rest of the orange you want to ‘feed’ your cake so take a spoon and  carefully pour it over the top of the cake. 

Into a small mixing bowl add the butter and beat with a wooden spoon until loose.  Add the mascarpone and beat again until just combined and no lumps.  Add the reserved orange and the icing sugar and mix until just combined.  You don’t want to overbeat this mixture as it will go runny.

When your cake is completely cool, top with the icing and cut into pieces.  I got 12 pieces but again, cut as large or small as you like.