Peel and Cut Potatoes: Start by peeling the red potatoes. Cut them into equal-sized, big chunks.
Rinse Potatoes: Rinse the cut potatoes with fresh water a few times to remove any excess starch.
Boil Potatoes: Season the water with salt and boil the potatoes until they are fork-tender, which could take 15-25 minutes depending on the size of the chunks.
Warm Up Dairy: While the potatoes are cooking, warm up the dairy. Combine the whole milk, heavy cream, and butter in a small pot over medium heat. Heat until the butter is melted and the mixture is hot. Set aside.
Drain and Steam Potatoes: Once the potatoes are fork-tender, drain them and let them sit and steam for 3-4 minutes to dry out a bit more.
Rice Potatoes: Use a ricer to process the potatoes until fine. Place the cooked potatoes in the ricer and squeeze to push them through.
Mix with Dairy: Pour the hot dairy mixture over the riced potatoes. Use a rubber spatula to gently mix everything together until the texture is right. Avoid overmixing to prevent the potatoes from becoming gummy.
Season: Taste and adjust the seasoning with more salt if necessary.