In a large skillet melt the butter. Add the pork and brown for 2 minutes on each side. Remove from the skillet and tent loosely with foil.
Add the mushrooms and sauté until they are soft, about 4 to 6 minutes.
Whisk in the flour and then very slowly whisk in the chicken stock. Add just a few tablespoons at a time, whisking to combine it, until it is completely added.
Whisk in the milk, garlic powder, onion powder, salt and pepper. Taste the sauce and add more salt or pepper to taste.
Add the pork back to the skillet.
Bring to a simmer, and cook, stirring often, over low heat for 10 to 12 minutes or until the pork reaches 145 degrees with an instant read thermometer.
Serve over noodles.