- Cook the carrots and swede together in a pan of boiling salted water for 20–25 minutes, until tender.
- Drain and return to the pan.
- Add the butter and horseradish, mash well and season to taste.
- For a lactose-free version, use 1 tbsp olive oil rather than butter and Dijon mustard instead of horseradish.
- You can make this the day before you need it then microwave or bake in an ovenproof dish.
- Freezing instructions: Defrost then heat in the microwave to serve.