In a large pot place the potatoes, then cover with cold water and salt the water. Place on the oven on high heat, once the water comes up to a boil lower the heat and continue to cook about 10-15 minutes or until you poke the potatoes with a knife and they are tender. The knife should be able to slide into the potato easily. Once they are cooked drain the potatoes and place them back into the pot.
Add in the butter, mascarpone cheese, Parmigiano Reggiano, roasted garlic, chives, parsley, salt and pepper. If the potatoes are too thick simply add some chicken stock or milk to loosen them up.