Prep the potatoes: Peel and cut the potatoes into even chunks, roughly 1 1/2-inch pieces. Rinse under cold water to remove excess starch.

Cook the garlic: Add the peeled garlic cloves to a small saucepan with the olive oil and a splash of water. Cook over low heat, stirring occasionally, until the garlic is soft and pale golden, 10–12 minutes. Set aside and reserve the oil.

Boil the potatoes: Place potatoes in a large pot and cover with cold water by about 1 inch. Add 2 teaspoons kosher salt. Bring to a gentle boil and cook until the potatoes are very tender when pierced, 15–20 minutes.

Warm the dairy: In a small saucepan, gently heat the cream (and milk if using) until warm but not boiling. Warm dairy blends more smoothly into potatoes.

Drain well: Reserve 1/2 cup of the starchy cooking water. Drain the potatoes, then return them to the warm pot over low heat for 1 minute, shaking the pot to evaporate excess moisture.

Mash the garlic: Using a fork, mash the softened garlic into a paste with a pinch of salt. This helps it blend evenly into the potatoes.

Mash the potatoes: Use a potato ricer for the fluffiest texture, or a masher for a more rustic feel. Avoid a food processor; it can make potatoes gluey.

Add butter and garlic: Add the softened butter, the mashed garlic, and the reserved garlic oil to the potatoes. Fold gently until the butter melts.

Add cream: Pour in warmed cream a little at a time, stirring gently until the potatoes are creamy and smooth. If needed, loosen with a splash of the reserved cooking water.

Season and finish: Taste and add salt and pepper. For a brighter finish, stir in a spoonful of chopped chives or parsley. Serve warm.