Boil the potatoes until they are soft. I like to leave the skin on for a more rustic appeal.
Place the potatoes in a bowl. You can use a potato masher or just a fork. Throw in some butter. Add in cut up pieces of the cheese and the rosemary leaves. Mix to allow the cheese and butter to melt.
Add in a cup or more if you like it more creamy of the half & half or milk. Then add in salt and some pepper. Mix well and serve.