Add the potatoes to a large pot and cover with cold water. Bring to a boil, then simmer until the potatoes are fork tender.

Drain the potatoes and mash with a potato masher. For even smoother potatoes, pass them through a potato ricer or whip them in a stand mixer. Be careful not to whip them too long, or they may become gluey.

Heat the cream, milk, butter, salt, and olive oil in a saucepan over medium heat until warm, then slowly add the warm liquids to the mashed potatoes.

Fold in the grated Manchego cheese and adjust the salt to taste.

Serve immediately and enjoy!