Fill and boil your kettle. Trim and peel the swede, then chop into 1cm-thick dice. Trim the celeriac, slice the roots off while trying not to remove too much flesh. Peel the celeriac, then chop it to match the swede.

Tip the vegetable stock powder into a heatproof jug. Pour in 500ml hot water and stir to dissolve the vegetable stock powder.

Place a deep frying pan or shallow casserole dish on a medium heat. Add 2 tbsp oil and the swede and celeriac. Season with salt and pepper and fry, stirring often, for 10 mins till the veg are lightly browned all over.

Pour in the vegetable stock and drop in the bouquet garni. Cover the pan with a lid, turn up the heat and bring to the boil. Once it’s boiling, turn the heat down and simmer for 15-20 mins, till the veg are tender. Meanwhile, dice 100g of the butter.

When the veg are tender, drain them then return to the pan. Pick out and discard the boquet garni.

Pop the pan on a low heat and warm for 1-2 mins, stirring often, to sizzle off any excess water. Add the butter. Take the pan off the heat and use a masher to mash the veg together.

When the mash is smooth, taste and add more salt or pepper, if needed. Spoon the mash into a warm bowl and serve.