Once chicken is done, you can either do a quick-release of pressure or let it manually release. Either way, once the pressure is released, carefully lift out the chicken and place on a large casserole dish. Leave the liquid in the insert as you can make a gravy out of it later!
Using your a brush or your hands (if you deem that the chicken is not too hot), spread the butter mixture all over the chicken. Making sure it gets in the nooks and crannies and the inside cavity.
Bake in the oven for an additional 15-20 minutes to get the exterior nice and brown. You can choose to broil the exterior, too, but watch it as it takes less time.
Let chicken rest for 15 minutes before carving and serving.
For the liquid that is still in the pressure cooker insert: turn your pressure cooker to the saute function (if you don't have that, you can pour the liquid into a small saucepan and this on the stove) then add 2-3 tablespoons of flour to the mixture to thicken into a gravy-like consistency. If you like it thicker, add more flour. Season with additional salt and pepper, to taste.