To make the biscuits: Heat the oven to 450F.
Line a baking sheet with parchment paper.
In a large bowl, combine the flour, baking powder and salt and whisk to combine.
Add the cold butter and incorporate with a pastry cutter, fork or your fingers until it resembles fine crumbs.
Stir in the buttermilk with a wooden spatula.
Transfer the dough to a floured surface and roll out with a rolling pin.
Cut into 9 to 10 biscuits. I used a pizza cutter to cut them into squares, but you can use a round biscuit cutter, too.
Place the biscuits on the prepared baking sheet. Brush the tops with melted butter.
Bake the biscuits in the oven for 15 to 17 minutes, until golden brown.
To make the pot pie soup: Add the olive oil to a large soup pot over medium-high heat.
Add the diced chicken and cook until golden brown and cooked through. Remove the chicken from the pot.
Add the butter to the remaining olive oil and melt.
Add the diced onion, carrots, celery, and mushrooms and stir to combine.
Cook for 10 minutes, until the vegetables have softened, stirring occasionally.
Add the garlic, salt, and pepper and stir well to combine, cooking 1 more minute.
Add the flour, stirring to combine and cook for 1 minute.
Slowly add the chicken broth, stirring constantly to incorporate with the vegetable mixture.
Add the chicken and peas to the pot, bring the mixture to a boil and simmer for 5 minutes.
Stir in the cream or milk.
Serve with the biscuits and enjoy!