Be sure to bake the potatoes until they are completely tender; err on the side of over- rather than undercooking. You can use a hand-held mixer instead of a standing mixer, but the potatoes will be lumpier.
1. Adjust an oven rack to the middle position and heat the oven to 450 degrees.
2. Microwave the potatoes on high power for 16 minutes, turning them over halfway through the cooking time. Transfer the potatoes to the oven and place them directly on the hot oven rack. Bake until a skewer glides easily through the flesh, about 30 minutes, flipping them over halfway through the baking time (do not undercook).
3. Remove the potatoes from the oven, and cut each potato in half lengthwise. Using an oven mitt or a folded kitchen towel to hold the hot potatoes, scoop out all of the flesh from each potato half into a medium bowl. Break the cooked potato flesh down into small pieces using a fork, potato masher, or rubber spatula.
4. Transfer half of the potatoes to the bowl of a standing mixer fitted with the paddle attachment. Beat the potatoes on high speed until smooth, about 30 seconds, gradually adding the rest of the potatoes to incorporate, until completely smooth and no lumps remain, 1 to 2 minutes, stopping the mixer to scrape down the sides and bottom of the bowl as needed.
5. Remove the bowl from the mixer and gently fold in 2 cups of the cream, followed by the butter and 2 teaspoons salt. Gently fold in up to 1/2 cup more of the cream as needed to reach your desired serving consistency. Once the desired serving consistency is reached, gently fold in an additional 1/2 cup cream.
6. To Store: Transfer the mashed potatoes to a large microwave-safe bowl and cover tightly with plastic wrap. Refrigerate for up to 2 days.
7. To Reheat: Poke lots of holes in the plastic wrap with the tip of a knife, and microwave at medium-high (75 percent) power until the potatoes are hot, about 14 minutes, stirring gently halfway through the reheating time.