Ultra-Creamy Buttermilk Parsnip and Potato Mash with Garlic

Why You’ll Love This Recipe

• Ultra-creamy texture with a bright, tangy lift from buttermilk.
• Slow-roasted garlic melts in for deep, sweet-savory flavor.
• Cozy, elegant side that feels special but is easy for any home cook.
• Perfect make-ahead mash that reheats beautifully for stress-free dinners.

Grocery List

• Produce: Yukon Gold potatoes, parsnips, 1 head garlic, fresh chives
• Dairy: Buttermilk, unsalted butter
• Pantry: Olive oil, kosher salt, fine sea salt, white pepper (or black pepper)

Full Ingredients

Roasted Garlic

• 1 large head garlic
• 1 teaspoon olive oil
• Pinch of fine sea salt

Parsnip-Potato Mash

• 2 lb (900 g) Yukon Gold potatoes, peeled and cut into 1.5-inch pieces
• 1.5 lb (680 g) parsnips, peeled and cut into 1.5-inch pieces (trim woody cores if very thick)
• 2 tablespoons kosher salt (for the cooking water)

Warm Buttermilk-Garlic Butter

• 6 tablespoons (85 g) unsalted butter, divided (5 tbsp for mash, 1 tbsp for drizzling)
• 1 1/4 cups (300 ml) buttermilk
• 1/2 teaspoon white pepper
• Fine sea salt, to taste (start with 1 teaspoon and adjust)
• 3 tablespoons finely snipped chives, plus more for garnish

Step-by-Step Instructions

Step 1: Slow-roast the garlic

Heat the oven to 325°F (165°C). Slice the very top off the garlic head to expose the cloves. Place on a small sheet of foil, drizzle with 1 teaspoon olive oil, and sprinkle with a pinch of salt. Wrap tightly and roast on a small tray until the cloves are deep golden and jammy-soft, 60–75 minutes. Cool just until handleable, then squeeze the cloves from their skins. Mash to a paste and reserve.

Step 2: Prep and start the vegetables

Peel the potatoes and parsnips and cut into 1.5-inch chunks. If any parsnips are very thick, quarter lengthwise and trim the woody core. Place both vegetables in a large pot, cover with cool water by about 1 inch, and add 2 tablespoons kosher salt. Set over medium-high heat and bring to a gentle boil.

Step 3: Simmer until tender

Reduce to a steady simmer and cook until a paring knife slides in without resistance, 18–22 minutes. Check a piece of potato and a piece of parsnip to ensure both are tender.

Step 4: Drain and dry for extra fluff

Drain thoroughly. Return the vegetables to the hot pot and place over low heat for 1–2 minutes, shaking occasionally, to steam off excess moisture. This step keeps the mash from turning watery.

Step 5: Warm the buttermilk, butter, and garlic

In a small saucepan over low heat, combine the mashed roasted garlic, 5 tablespoons butter, and the buttermilk. Heat gently just until hot to the touch (about 120°F/49°C). Do not simmer—keeping it warm prevents curdling and helps the mash become ultra-creamy.

Step 6: Mash, then whip gently

Rice the potatoes and parsnips back into the warm pot (or mash by hand). Gradually fold in the warm garlic-buttermilk mixture until silky and loose enough to just hold soft peaks. Season with 1 teaspoon fine sea salt and 1/2 teaspoon white pepper, then taste and adjust. Avoid overmixing; use a spatula or a hand mixer on low only briefly to aerate.

Step 7: Finish and serve

Fold in 3 tablespoons chives. Melt the remaining 1 tablespoon butter and drizzle over the top. Add a final scatter of chives. Serve hot.

Pro Tips

• Start the vegetables in cold, salted water for even cooking from edge to center.
• If your parsnips are very thick, trim the tough inner core for a smoother mash.
• Dry the drained vegetables in the hot pot; evaporating surface moisture is key to creamy, not watery, results.
• Warm the buttermilk gently (do not boil) to avoid curdling and to help it absorb smoothly.
• For the silkiest texture, use a ricer or food mill; never a blender, which can make potatoes gluey.

Variations

• Brown Butter and Thyme: Brown 6 tablespoons butter with 1 teaspoon fresh thyme leaves; use in place of regular melted butter.
• Parmesan and Crème Fraîche: Stir in 1/2 cup finely grated Parmesan and 1/4 cup crème fraîche with the buttermilk for rich, tangy depth.
• Horseradish and Dill: Fold in 2–3 tablespoons prepared horseradish and 1 tablespoon minced dill for a steak-night side with zip.

Storage & Make-Ahead

Refrigerate leftovers in an airtight container for up to 4 days. Reheat gently on the stovetop over low heat or in the microwave at 50% power, stirring occasionally; splash in a little warm buttermilk or milk to loosen. The roasted garlic can be made up to 4 days ahead and refrigerated. For make-ahead serving, hold the finished mash in a covered, warm bowl or slow cooker on the “warm” setting for up to 2 hours, stirring occasionally. Mashed parsnips and potatoes freeze fairly well; freeze up to 1 month and thaw overnight in the refrigerator before reheating and re-whipping with a spoonful of warm buttermilk.

Nutrition (per serving)

Approximate values: 330 calories; 15 g fat; 46 g carbohydrates; 5 g protein; sodium varies by salt added.