Cold leftover mashed potatoes can be reheated right back to their former hot, creamy, and smooth state. ... For best results, skip the microwave—the high heat tends to suck the moisture out of mashed potatoes—and reheat them on the stovetop or in the oven.

Why is it bad to reheat mashed potatoes?

Sad news for spud lovers: reheating leftover potatoes could make you ill. As the Independent reported, the issue with reheating potatoes isn't actually the process of warming them in the microwave or oven. If cooked potatoes are left to cool at room temperature for too long, the bacteria that causes botulism may form.

How do you reheat leftover mashed potatoes?

Oven method:

If you refrigerated your mashed potatoes in an oven-safe casserole dish, set them out on the counter to take the chill off for at least 20 minutes before you pop them into the oven. When you're ready, bake, covered, at 350 degrees for 15 to 20 minutes, or until the potatoes are hot throughout.