"Starchy potatoes, like russets, have high starch and low water. Starchy potatoes are great for baking and French fries, and good as mashed potatoes. When cooked in water, they disintegrate; when cooked by dry heat, they become crumbly and fluffy. All-purpose, or chef's potatoes, like Yukon Golds, have medium starch and medium water. All-purpose potatoes are great in stews, soups, mashed potatoes, or for roasting. When cooked, they are at once moist and fluffy: they keep most of their shape in soups and don't dry out when baked."
Here's our recipe for perfect Thanksgiving mashed potatoes:
3 lbs Yukon Gold potatoes, peeled and quartered length-wise
1 teaspoon salt
8 Tbsp heavy cream
4 Tbsp butter
2 Tbsp milk
Salt and pepper
Put potatoes into a saucepan. Add 1 teaspoon salt. Add water until potatoes are covered. Bring to boil, reduce heat and simmer, covered, 15-20 minutes, or until done - a fork can easily be poked through them.
Warm cream and melt butter, together, either in microwave or in a pan on the stove. Drain water from potatoes. Put hot potatoes into a bowl. Add cream and melted butter. Use potato masher to mash potatoes until well mashed. Use a strong spoon to beat further, adding milk to achieve the consistency you desire. (Do not over-beat!.) Salt and pepper to taste.