Potato–and–Celery Root Biscuits


Chadwick Boyd's biscuits get an upgrade from a thyme-infused mash of potatoes, celery root, and cream. Substitute 1 1/2 cups mashed potatoes, if desired. Run your hands under very cold water and dry well before working butter into flour in step 2 and working the dough in step 3. "This is the granny method," says Boyd. "It's the tactile way of merging the butter and flour—with your hands. You literally snap it between your fingers and thumb."

Potato and Celery Root Biscuits
Photo: Photo by Jennifer Causey / Food Styling by Torie Cox
Active Time:
40 mins
Total Time:
5 hrs 30 mins
16 biscuits


Potato–Celery Root Mash

  • 1 ½ cups chopped (1/2-inch pieces) peeled Yukon Gold potatoes

  • 1 cup chopped (1/2-inch pieces) peeled celery root

  • 1 cup heavy cream

  • ¼ cup water

  • ¾ teaspoon fine sea salt

  • 2 tablespoon unsalted butter

  • 4 to 5 (6-inch) thyme sprigs


  • 2 ¼ cups all-purpose flour (about 9 5/8 ounces), plus more for dusting

  • 1 tablespoon plus 1 teaspoon cream of tartar

  • 1 teaspoon baking soda

  • 1 teaspoon fine sea salt

  • ½ teaspoon cracked black pepper

  • 6 tablespoons unsalted butter (3 ounces), chilled and cut into 1/2-inch cubes

  • 1 cup plus 2 tablespoons heavy cream, chilled, divided

  • ½ teaspoon flaky sea salt

  • Small tender thyme sprigs, for garnish (optional)


Make the potato–celery root mash:

  1. Stir together potatoes, celery root, cream, 1/4 cup water, and fine salt in a 2-quart saucepan. Add butter and thyme sprigs. Bring to a boil over medium-high. Reduce heat to medium to maintain a vigorous simmer, and cook, uncovered, stirring often to prevent bubbling over, until vegetables are very soft, and liquid has almost completely reduced, 18 to 20 minutes. Remove from heat. Let cool 5 minutes. Remove and discard thyme. Using a potato masher or fork, mash mixture until mostly smooth. Transfer mash to a medium bowl. Press plastic wrap directly onto surface. Chill until cold and thickened, at least 4 hours.

Make the biscuits:

  1. Preheat oven to 425°F. Whisk together flour, cream of tartar, baking soda, fine salt, and pepper in a large shallow bowl. Add butter, and toss to coat in flour mixture. Working quickly to keep butter cold, pinch and snap butter cubes into flour mixture using your fingertips to form small, crumbly, pea-size pieces. Add 1 1/2 cups chilled potato–celery root mash and 1 cup cream. Using a sturdy rubber spatula, stir mixture until a shaggy dough forms, adding remaining 2 tablespoons cream, 1 tablespoon at a time, if needed to bring dough together. Chill, uncovered, 20 minutes.

  2. Turn dough out onto a lightly-floured work surface. Sprinkle top of dough with flour, and pat into an 8-inch square. Lightly flour a sharp chef's knife; cut dough into quarters. Stack quarters on top of each other, and press down into an 8-inch square. Repeat process 3 times, re-flouring work surface as needed. Trim about 1/4 inch off sides of dough square to straighten; discard scraps. Cut dough into 16 (about 2-inch) squares, and arrange 3/4 inch apart on a baking sheet lined with parchment paper.

  3. Sprinkle biscuits with flaky salt; garnish with thyme sprigs, if desired. Bake in preheated oven until golden brown, 20 to 25 minutes. Let cool on pan 5 minutes.

Make Ahead

Mash can be made up to 3 days ahead and refrigerated in an airtight container.

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