1 Make the dumpling batter: Whisk together the flour, baking powder, and salt in a medium bowl.
Add melted butter to the dry ingredients, using your fingers to distribute it throughout the flour until it has a crumbly texture.
Add the milk. If you are using all-purpose flour, another tablespoon or two of milk may be required to make the dough sticky, rather than dry and shaggy. Gently mix with a wooden spoon, until the mixture just comes together. It should form a lumpy, thick batter. Do not over-mix, or your dumplings will turn out too dense. Set aside.
2 Sauté the vegetables and chicken in the pressure cooker: Heat the oil in the pressure cooker on its sauté setting for 1 minute. Add the onion, celery, carrots, salt, and pepper and sauté for 3 minutes, until the onions are beginning to soften around the edges.
Add the chicken and thyme and sauté for 2 more minutes, until the pieces of chicken are mostly opaque on the outside (they don’t have to be cooked through). Stir in the chicken broth, using a spoon to thoroughly nudge any browned bits off of the bottom of the pot.
3 Add the dumplings and pressure cook: Using a small cookie scoop or two spoons, drop heaping tablespoon-sized dollops of the dumpling batter into the pot in a single layer. (The batter will have thickened while it sat, becoming more of a scoop-able dough.)
4 Pressure cook: Secure the lid in its sealed position. Cancel the sauté program, then select the pressure cooker’s manual program for 8 minutes at high pressure.
(The pot will take about 10 minutes to come up to pressure before the cooking program begins.)
When the cooking program ends, let the pressure release naturally for 10 minutes, then move the pressure release valve to its venting position to release any remaining steam.
5 Finish the dish: Open the pot and gently stir in the peas, parsley, and cream (if using), taking care not to break up the dumplings. Taste for seasoning, adding more salt and/or pepper if needed. Ladle into bowls and serve right away.