Whisk 1½ cups all-reason flour, 2 tsp. baking powder, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt in a large bowl to merge. Add 6 Tbsp. chilled unsalted butter, reduce into items, and toss to coat. Do the job in butter with your fingers until finally mixture resembles coarse crumbs. Add ½ cup furthermore 2 Tbsp. hefty cream and stir with a fork right up until a shaggy dough kinds and no dry bits of flour continue being. Chill 20 minutes.
Do forward: Dough can be designed 2 times ahead. Include tightly and continue to keep chilled.
Filling and assembly
Spot a rack in middle of oven preheat to 450°. Warmth 1 Tbsp. vegetable oil in a 10″ forged-iron skillet in excess of medium-high. Time 1 lb. skinless, boneless rooster thighs (about 4) on each sides with ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt. Prepare chicken thighs in pan in a single layer and cook dinner, undisturbed, until eventually golden brown beneath, 5–7 minutes. Change more than and cook until practically cooked by, about 4 minutes. (Chicken will complete cooking by means of in the oven.) Transfer to a slicing board permit interesting slightly, then slice into 1″ parts.
Lessen heat to medium and melt 1 Tbsp. unsalted butter in pan (no want to clear). Add 1 compact onion, minimize into ½” items, 1 medium carrot, scrubbed, slice into ½” items, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt and stir to coat. Cook dinner, stirring frequently, until finally onion is translucent, about 3 minutes. Add 1 medium (5–8 oz.) waxy potato (these kinds of as purple), slice into ½” parts, 2 celery stalks, slice on a diagonal into ½” pieces, 2 garlic cloves, finely chopped, 1 tsp. dried thyme, ½ tsp. freshly ground pepper, and remaining 1 Tbsp. unsalted butter. Cook, stirring, 1 moment, then increase 2 Tbsp. all-objective flour and stir to coat greens. Prepare dinner, stirring normally, right until flour coating is golden and nutty-smelling, about 3 minutes.
Increase ½ cup dry white wine, scraping up any browned bits from bottom of pan. Provide to a boil and prepare dinner until finally wine is decreased by half, about 2 minutes. Insert 1 cup low-sodium chicken broth or water and carry to a simmer. Minimize heat to reduced, include pan, and cook dinner right until mixture is thickened a bit, about 4 minutes.
Uncover pan and stir rooster, coarsely chopped celery leaves (if utilizing), ½ cup heavy product, and ½ cup refreshing or frozen peas into filling. Taste and period with additional kosher salt if desired.
Dollop golf-ball–size pieces of dough around filling. Brush with cream and year with pepper and flaky sea salt (if using). Area skillet on a baking sheet to catch any drips and transfer to oven. Bake right up until biscuits are golden brown and filling is effervescent, 25–30 minutes. Let great marginally prior to serving.