Step 1

Preheat oven to 400 degrees F. Spray a 9x13 baking dish with nonstick spray.

Step 2

Add 4 tablespoons of butter into a large pot to melt. Add onions and celery and sauté for 5 minutes, until vegetables have softened. Add the frozen vegetables and sauté for an additional 5 minutes.

Step 3

Sprinkle ½ cup flour, salt, and pepper over sautéed vegetables and stir to coat evenly. Stir constantly for 2 minutes, letting the flour cook a bit. This mixture will be thick and pasty.

Step 4

Pour in chicken stock and stir mixture constantly as it comes to a low boil.

Step 5

Reduce heat to medium low and add the milk, stirring constantly.

Step 6

Add the chicken to the pot and stir to combine. Simmer for 15 minutes, stirring occasionally, while making the biscuits. Taste and season with additional salt and pepper, if needed.

Step 7

Carefully pour the filling into the prepared baking dish. Top with the biscuits. Lightly brush the biscuit tops with 2 tablespoons of melted butter.

Step 8

Bake for 20 minutes, until the filling is bubbly, and the biscuits are golden brown. Gently lift the top of a biscuit to make sure that the biscuit is cooked through and not too gooey on the bottom. It will be a bit wet, of course, but should not be gooey.

Step 9

Let sit for 5 minutes before serving.

Step 10

Add the flour, baking powder, sugar, and salt to a large bowl and stir together with a fork.

Step 11

Grate the cold butter on a box grater and add to the flour mixture.

Step 12

Pour the buttermilk into the flour mixture and stir with a fork until a dough forms.

Step 13

Turn the dough out onto a lightly floured work surface. Pat or roll the dough out into a rectangle about ½ inch thick. Fold the dough over on itself and pat or roll it back down to ½ inch thick. Repeat this process 3 or 4 times for flaky layered biscuits, ending with the final layer rolled out to about ¾ of an inch thick.

Step 14

Cut into 12 biscuits using a 3-inch cutter on a floured surface. Press the biscuit cutter straight down without twisting for the best results. You may need to reroll the dough to get 12 biscuits.