1/2 - 3/4cupsevaporated milk, warmed (or use cream or half and half)
salt and freshly ground black pepper, to taste
Cut potatoes in half and place in a large pot with about 4 inches of water (they don't need to be completely covered). Cover pot with a lid, and cook, covered, until fork tender, about 15-20 minutes. You don't want them "mushy" or falling apart.
Drain water completely from pot and leave potatoes in the pot, covered with a lid, for about 10 minutes. This gives them time to dry out, which helps them to be extra fluffy.
Remove lid and add butter, chicken bouillon, evaporated milk, sour cream and salt and pepper.
Mash with a potato masher. Taste and add more salt and pepper, if needed, or more milk, until they are creamy, fluffy and smooth.
I use an electric mixer to beat them on medium speed for about 30 seconds, until light and fluffy. But, be careful not to over-mix them or they will get starchy and gummy.
*I use Better then bouillon base (chicken flavor).To make ahead:Add a little extra milk to make sure they're really soft and not too thick. (The potatoes will absorb moisture as they rest.) Spoon mixture into a casserole dish or large tupperware. Cover and refrigerate for 1-2 days.Remove from fridge 1 hour before baking. Taste and add additional seasonings as needed, or milk, to make sure theya re nice and soft. Bake, covered, at 350 degrees for 20-30 minutes or until warm.You could also reheat them in a saucepan on the stove, or in the microwave.