To a large pan add a glug of oil, once hot add in the chopped onion, carrots, celery and garlic. Fry on a medium heat for 10 minutes. Add in the sliced mushrooms and thyme leaves. Cook for another 10 minutes until all the water has evaporated.
Add the nuts together with the stock cube and Colman's Mustard Powder to a food processor. Pulse few times until you have a rough crumble. Add in the cooked veggies together with the chestnuts to the food processor and pulse again until you have a sticky mixture but not too mushy.
Pour the mixture into a bowl and add the dried cranberries, breadcrumbs, soy milk and season with salt and pepper. Mix everything together.
Spoon the mixture into a loaf tin lined with baking paper and press it down until is all compact. Cover with some foil and bake in the oven at 180 degrees Celsius for 30 minuets. Remove the foil and continue baking for another 10 minutes.