Start by peeling both carrots and swede and cutting them into chunks. Make sure they're of similar size so that they cook evenly.
Put all the prepared veg into a saucepan and cover with water (just to cover the veg). Add couple of pinches of salt or a scant teaspoon, cover and bring to boil.
Simmer for approx. 20 minutes or until all the veg is fork tender.
Once cooked, drain the veg in a colander.
Next, return veggies to the pan and back onto the hob/stovetop on a low heat for a few seconds giving a pan a little shake to let the veg steam and dry out a bit.
Mash the veg with potato masher or immersion blender. The latter will give you a smoother texture.
Add some fresh thyme leaves and butter and mix them into the mash with a wooden spoon.
Last but not least, grate some nutmeg into the mash and mix it in (remember, less is more with nutmeg). Taste and adjust seasoning with salt and pepper to taste.
Feel free to add some plant cream at this point as well.
Serve and enjoy!