Here's what I used:
Bag of Oreda Steam & Mash Potatoes
Now, you could always use regular potatoes to start this out, but I had these on hand, buried in my freezer, and they cook in the microwave, less hassle for me!
You can also use regular cream cheese, I just happened to have the Neufchatel on hand.
You could also use whatever sort of cheese you had, I think any would work equally.
Now, start by popping the potatoes in the microwave, according to package directions (mine took 10 minutes on high). While they are doing their thing, go ahead and cube up your Neufchatel and shred your cheese:
Once your potatoes are done, wait about 2 minutes, then carefully pop open the bag, and dump them into a bowl with your milk & butter blend (use quantities recommended from package).
You can mash these by hand, or mixer. If I'm making regular mashed potatoes, I usually will just do them by hand, so as not to overwork them, but since I was going to be incorporating other ingredients and wanted it to be smooth, I used my KitchenAid. Once you get the potatoes started, and they're about halfway mashed, go ahead and add in your cream cheese (8 oz block cubed), shredded cheese (about 2 oz), sour cream (I just grabbed a big spoonful), and the onion powder (I just sprinkled some in, I'm guessing, about a half a tsp):
Bake @ 350 for about 20-30 minutes, until heated through. Serve