Note on freezing: If you freeze and then defrost, you may need to stir up the mashed potatoes before baking. See above for more detailed freezing and reheating instructions.
- 4 to 5 pounds potatoes (russets, yukon gold or a combination), peeled and cut into 2-inch chunks
- 3 garlic cloves, peeled and whole
- 1 small sprig fresh rosemary
- 3 tablespoons unsalted butter, divided 2 tablespoons and 1 tablespoon
- 8 ounces cream cheese (full fat), room temperature
- 1/2 cup plain or greek yogurt (or sour cream)
- 1/4 teaspoon fresh minced rosemary
- 2 teaspoons kosher salt
- 1/8 teaspoon freshly ground black pepper
- Chives for garnish
1 Cook the potatoes: Place peeled cut potatoes in a large saucepan, cover with an inch of cold water. Add 2 teaspoons of salt to the water. Add the garlic cloves and rosemary sprig.
Heat on high to bring to a boil, then reduce to low, cover to maintain a simmer until the potatoes are just cooked through, about 10 to 12 minutes.
Once potatoes are done, drain the potatoes. Discard the rosemary sprig, save the garlic cloves with the potatoes.
2 Mash the potatoes and garlic cloves: While the potatoes are still hot, use either a potato masher or a potato ricer to roughly mash the potatoes and the garlic cloves in a large bowl.
A ricer will yield fluffier, less gluey, mashed potatoes.
3 Mix in cream cheese and yogurt: In a large upright mixer (or if you have strong arms, you can do this by hand), add the riced or roughly mashed potatoes into the mixer bowl, along with 2 tablespoons of butter, the softened cream cheese, and the yogurt.
Mix on low to start, then increase the speed to medium and mix just until everything is well incorporated. (Don't overmix!)
Stir in the minced rosemary, the salt and pepper. Taste and add more salt and pepper if needed.
4 Place in casserole dish: Butter generously the inside of a 2-quart casserole dish. Add the mashed potatoes, and spread out in an even layer. Dot with the remaining 1 Tbsp butter.
At this point, you've done the make-ahead part of the recipe. You can cover with plastic wrap and chill until ready to bake. You can make up to 2 days ahead. (Or you can freeze for up to 2 weeks ahead; see headnotes for more detailed freezing and reheating instructions.)
5 Bake: When ready to make, remove from refrigerator and let sit for an hour to come to room temperature. Bake at 350°F for 30 to 45 minutes, until the top is lightly browned.