Chicken-And-Biscuit Casserole

Ingredients

FILLING

1/4 cup unsalted butter

1 3/4 cups chopped yellow onion (from 1 medium [10 oz.] onion)

1 cup chopped carrots (from 2 medium [5 oz. each] peeled carrots)

1 cup diagonally sliced celery (from 2 medium [3 oz. each] stalks)

1/4 cup all-purpose flour

2 1/2 tsp. garlic powder

3/4 tsp. dried thyme

1/2 tsp. dried rosemary

3 cups whole milk

3 cups shredded rotisserie chicken

1 cup frozen sweet peas (from 1 [10-oz.] pkg.)

1 tsp. kosher salt

1/2 tsp. black pepper

Cooking spray

BISCUITS

2 cups (about 8 1/2 oz.) all-purpose flour

1 Tbsp. baking powder

1 tsp. granulated sugar

1 tsp. kosher salt

10 Tbsp. (5 oz.) unsalted butter, frozen

1 1/2 oz. shredded Gruyère cheese (about 1/3 cup)

1 1/2 oz. shredded sharp Cheddar cheese (about 1/3 cup)

3/4 cup whole buttermilk, plus more as needed

2 Tbsp. finely chopped fresh chives

Directions

Cook vegetables: Preheat oven to 425°F. Melt butter in a large skillet over medium. Add onion, carrots, and celery; cook, stirring often, until softened, about 6 minutes.

Add seasonings: Stir in flour, garlic powder, thyme, and rosemary; cook, stirring constantly, until vegetables are coated and mixture is fragrant, about 1 minute.

Add milk: Gradually whisk in milk, whisking constantly, until smooth and slightly thickened, about 3 minutes.

Finish Filling: Stir in chicken, peas, salt, and pepper until just combined. Remove from heat.

Spoon Filling into a baking dish: Transfer to an 11- x 7-inch baking dish coated with cooking spray; place on a large, rimmed baking sheet.

Bake: Cover with aluminum foil, and bake in preheated oven on a baking sheet until heated through, about 10 minutes.

While casserole bakes, prepare the Biscuits: Whisk together flour, baking powder, sugar, and salt in a large bowl until no lumps remain.

Grate butter: Grate frozen butter on large holes of a box grater.

Add butter and cheeses to flour mixture: Toss grated butter with flour mixture to evenly coat. Toss in Gruyère and Cheddar to evenly coat.

Make dough: Using a rubber spatula, stir in buttermilk and chives until a shaggy dough forms, about 1 minute (gently knead to incorporate, as needed). Add more buttermilk 1 tablespoon at a time, as needed, to come together.

Scoop Biscuits onto casserole: Remove casserole from oven, and discard foil. Immediately dollop 12 (1/4-cup) portions of Biscuit dough evenly onto hot casserole.

Finish baking: Return to oven; bake, uncovered, until mixture is bubbly and biscuits are golden brown, 25 to 30 minutes. Let stand 10 minutes. Sprinkle with chives. Serve hot.