Cut the potatoes into evenly-sized chunks (about an inch or so thick), and transfer them to a large stockpot full of cold water (and 1 tablespoon salt) filled so the water line sits about 1 inch above the potatoes.
Bring the water to a boil over high heat, reduce heat to medium-high (or whatever temperature is needed to maintain the boil) and continue cooking for about 10-12 minutes, or until a fork or knife inserted in the potato goes in easily.
While the potatoes cook, in a seperate pot, gently heat the butter, half and half, milk together (Do not boil).
Carefully drain the potatoes and add them back to the pot with the butter, and warmed milk mixture.
Mash the potatoes into the butter mixture with a ricer or potato masher. Combine by gently stirring with a wooden spoon or spatula to incorporate. The potatoes will gradually absorb the liquid and turn into a creamy mixture.
Add more butter, or half and half a little at a time until it reaches your desired consistency and creaminss. Taste for seasoning and add salt as needed. Serve warm.
Salt the water well. Potatoes absorb the cooking water as they cook. If your water doesn't have any flavor neither will your potatoes.
Always start with cold water when cooking potatoes. Using hot or boiling water will cause uneven cooking.
Evenly cut your potatoes before boiling. Large, whole potatoes won't cook evenly. So cut your potatoes into evenly sized smaller pieces for quicker, even cooking.
Use a fork and not a knife to check for doneness. A fork should slide easily into the potato when cooked. A knife is sharp and will slide into the potato even if it’s not cooked.
Don’t overcook the potatoes. As soon as a fork can be inserted easily into the potatoes, they’re ready to go.
Be sure to mash your potatoes as soon as possible after draining. Waiting too long will result in sticky, starchy mashed potatoes.
Don't use a blender, mixer, or food processor to mash potatoes. It can easily result in a very sticky, rubbery mash.