Steam or boil the potatoes and sweet potatoes until cooked. Note, the sweet potatoes will take less time than the potatoes. Drain, then mash with butter and seasoning until smooth. Allow to cool. If making vegan, mash with olive oil.
Heat the oil in a large pan and sweat the onion, carrots and celery for 10 minutes, stirring regularly. Alternatively, cook in the steamer.
Stir in the Heinz Beanz, vegetarian Worcester sauce, thyme, seasoning and heat gently for a further 10 minutes.
Add the peas then transfer to a tin and allow to cool slightly before piping over the sweet potato mash.
Cook for 20-25 minutes in a pre-heated oven at 200oC until bubbling and core temperature is reached.