In place of the chicken stock, you can use milk or sour cream or cream, maybe some butter or a combination of them.
To roast garlic add to this, slice the very top off a bulb of garlic. Place it in a bit of tin foil and drizzle the garlic with olive oil, salt and pepper. Make a foil tent and roast at 350 degrees for 20-25 minutes. When done, just squeeze the garlic from the bulb and mash it.
If you're making this for a crowd, you can peel and chop the potatoes ahead of time. Place them in a pot of cool water and let them hang out until you're ready to cook them.
For more tips and tricks, be sure to read the full article above.