Firstly, preheat the oven. Then, take a pan and add water, salt, and potatoes to it and then bring it to a boil.
When the potatoes are cooked, drain the water from the pan.
Now, take another pan and put it on medium flame. Add in the butter and melt. Then, toss in the cabbage and cook for 2-3 minutes till it gets soft.
Take out the cabbage and put it along with the potatoes, swede and more butter. Mash everything properly using a masher.
Season with salt and black pepper.
Top it with cheese and cover it. Bake it in the oven for 30 minutes, then uncover the vegetables and cook it further for 15 minutes until properly cooked and then serve.