Place prepared potatoes and parsnips in a large pot of cold water. Bring to a boil over high heat. Reduce heat and cook until vegetables are tender about 15 minutes. Heat milk and butter together in small saucepan. Using a potato masher, mash potatoes and parsnips. Gradually add milk along with Mrs. Dash® Lemon Pepper and continue to mash until vegetables are smooth and creamy. Serve immediately.