Preheat the oven to 425°F (≈ 220°C).

Dice the onion, celery, carrots, and potatoes into bite-size pieces.

In a large oven-proof pan (or Dutch oven or skillet that can go into the oven), melt the 3 tablespoons of butter.

Add the diced celery and onion to the butter and cook for about 5 minutes until beginning to soften.

Sprinkle the flour (⅓ cup), the salt (1 tsp), garlic powder (1 tsp), and pepper (½ tsp) over the cooked veggies and stir to combine.

Pour in the chicken broth (2 cups) and heavy cream (1 cup). Cook and stir until the sauce thickens (about 10 minutes).

Add the diced potatoes, carrots, shredded/diced cooked chicken (2 cups), and frozen peas (1 cup, if using). Remove the pan from heat.

Meanwhile prepare the biscuit topping: in a separate bowl, mix the biscuit mix (2 cups) with the milk (¾ cup) and shredded cheddar cheese (½ cup). You’re setting aside the seasoning packet from the biscuit mix for later.

Drop portions of the biscuit topping over the chicken-vegetable filling in the pan—covering evenly.

Place the pan in the preheated oven and bake for 14–18 minutes (until the biscuit topping is golden and cooked through).

While the biscuits bake, melt the remaining ¼ cup butter and combine it with the seasoning packet from the biscuit mix. After the pies come out of the oven, brush this seasoned butter over the biscuit topping for that extra flavour finish.

Let the assembled pot pie rest for a few minutes before serving—this helps the filling set and makes serving easier.