Pre-heat the oven to 220C/200C fan.
Wash the carrots and swede (500g each). Cut the swede in half and lay the vegetables out on a baking tray.
Bake the carrots and swede for about an hour until soft in the centre.
Remove from the oven and allow to cool slightly until they can be handled.
Scoop the centre from the roasted vegetables and place into a large bowl or pan.
Use a hand blender to whizz the vegetables until smooth (if you don't have a hand blender then you can also use a blender, masher or fork to achieve a similar effect).
Add the olive oil (1 tsp).
Season with salt and pepper.
Whizz (stir) to ensure that the oil and seasoning are evenly distributed. If the mash has cooled slightly then reheat on a gentle heat on the hob until hot through.