In a large saucepan, cover potatoes with water and bring to a boil. Reduce heat to a low boil and cook until a knife inserted slides off easily, approximately 15 minutes depending on size of the potato.

Place the cauliflower in a strainer or veggie steamer and place on top of the potatoes in the saucepan and cover with a lid to steam.

Drain potatoes. Transfer potatoes and cauliflower to a bowl and mash with a potato masher, adding salt and pepper. Add stock small amounts at a time until the preferred consistency is reached.