While i can't believe i'm about to give out my mom's recipe, i also feel like humanity needs more of this stuff… consider it a holiday "good deed".
What you need (depending on amount of servings):
*potatoes *whole milk *sour cream *swiss cheese
*parmesan cheese *pepper *salt
Normally, I calculate one medium potato per person (trust me, you'll want leftovers). Give them a good wash and peel.
While Grate the cheeses and slice peeled potatoes into 1/4 inch slices.
Now drumroll for the secret reveal... boil milk like you would water for pasta(yes, whole milk). Salt it, pepper it to taste and then put the potato slices in for about 45 min. Use a fork to see if they're ready (tender but still firm to handle).
Layer the potato slices, add a layer of sour cream, salt pepper, swiss cheese & parmesan cheese. Repeat until you're at the top of the dish. Remember to add extra cheeses to the top layer for an amazing crust.
Pop it in the oven at 350°F for about 15 minutes (or until cheese melts through). I precooked for a potluck party but you can leave it in until golden brown. Remember, everything in there is cooked so no need to worry.
Bottom line: You can't get this wrong!!!