Wash the potatoes and add them to a big pot of seasoned water. Bring the water to a boil and simmer on medium–high for about 15 to 20 minutes, or until a tender. While the potatoes are cooking, melt the butter in a small saucepan over medium-low heat. Add the sage leaves and let cook until leaves are crisp and the butter has turned to a brown colour, with a nutty smell. Pour into a bowl and set aside. Drain the potatoes and add the potatoes back into the hot pot, mash the potatoes with a potato masher, or if you like them whipped, use a hand mixer. Once all mashed, add the butter and sage mixture, sour cream, mix it together. Slowly add the whole milk, one tablespoon at a time, until you get the consistency you want. Season with salt and pepper, and top with a dollop of butter and sage. ENJOY!