Biscuit-Topped Chicken Pot Pie Casserole

Serves 6-8

For the Filling

3 tbsp unsalted butter
1 medium yellow onion, diced
3 carrots, peeled and sliced into half-moons
3 celery stalks, sliced
3 cloves garlic, minced
1/3 cup (45g) all-purpose flour
2 cups (480ml) chicken stock, preferably low-sodium
1 cup (240ml) whole milk (or half-and-half for extra richness)
1 ½ tsp fresh thyme leaves (or ¾ tsp dried)
1 tsp kosher salt
½ tsp black pepper
¼ tsp celery seed (optional, but excellent)
4 cups (about 500g) cooked, shredded or diced chicken (rotisserie chicken works perfectly)
1 cup (150g) frozen peas
¼ cup chopped fresh parsley

For the Biscuit Topping

1. Make the Filling

Preheat oven to 200°C (400°F) . Butter a 9×13-inch (3-litre) baking dish.
In a large deep skillet or Dutch oven, melt the butter over medium heat. Add onion, carrots, and celery. Cook, stirring often, for 6-8 minutes until softened. Add the garlic and cook 1 minute more.
Sprinkle the flour over the vegetables. Stir constantly and cook for 1-2 minutes to cook out the raw flour taste.
Slowly whisk in the chicken stock and milk. Add thyme, salt, pepper, and celery seed. Bring to a gentle simmer and cook, stirring often, for 5-7 minutes until the mixture thickens to a creamy gravy consistency.
Remove from heat. Fold in the shredded chicken, frozen peas, and parsley. Taste and adjust seasoning.
Pour the filling into the prepared baking dish, spreading it evenly.

2. Make the Biscuit Topping

In a large bowl, whisk together the flour, baking powder, baking soda, sugar, and salt.
Cut the cold butter into the dry ingredients using a pastry cutter or your fingertips until the mixture resembles coarse meal with some pea-sized butter lumps. Work quickly.
Pour in the cold buttermilk and stir with a fork just until a shaggy dough forms. Do not overmix.

3. Assemble the Casserole

Turn the biscuit dough out onto a lightly floured surface. Pat it into a rough rectangle about 2 cm (¾ inch) thick. Fold it over itself once or twice for flaky layers, then pat out again to the same thickness.
Cut the dough into 8-10 rounds with a floured biscuit cutter (or simply cut into squares with a knife — no re-rolling needed).
Arrange the biscuits evenly on top of the filling, leaving small gaps for steam to escape. Brush the tops with a little extra buttermilk and sprinkle with flaky sea salt.

4. Bake

Place the dish on a baking sheet to catch any drips. Bake for 20-25 minutes, until the filling is bubbly and the biscuits are puffed and deep golden brown. If the biscuits brown too fast, tent loosely with foil for the last 5 minutes.

5. Rest and Serve

Let the casserole rest for 10 minutes before serving (this helps the filling set slightly). Scoop generous portions and enjoy.

Rotisserie Chicken saves time — just shred it while you sauté the vegetables.
Frozen veggie shortcut: Use 2 cups of frozen mixed vegetables (carrots, peas, corn, green beans) instead of fresh.
Cheesy twist: Add 1 cup of shredded cheddar to the filling or sprinkle on top of the biscuits for the last 5 minutes of baking.
Make ahead: Prepare the filling a day ahead, refrigerate, then top with fresh biscuit dough just before baking. You may need an extra 5-10 minutes of bake time.