Clean & pierce potatoes. Microwave 10 on one side. Flip potatoes & microwave again for 5 - 10 more minutes, until soft. Let cool slightly. Melt butter. Add sour cream, cream cheese, milk, salt & pepper to butter. Slice the tops off the potatoes and scoop out the insides. Add to other ingredients and mash together. Refill potato skins & bake @ 350 for 10 - 15 minutes.