In a large skillet melt the butter. Add the chicken and brown for 2 minutes on each side. Remove from the skillet and tent loosely with foil.
4 tablespoons unsalted butter, 1 pound chicken tenderloins
Add the mushrooms and saute until they are soft, about 4 to 6 minutes.
8 ounces mushrooms
Whisk in the flour and then very slowly whisk in the chicken broth. Add just a few tablespoons at a time, whisking to combine it, until it is completely added.
3 tablespoons all purpose flour, 1 cup chicken broth
Whisk in the milk, garlic powder, onion powder, salt and pepper.
3/4 cup milk, 1/2 teaspoon garlic powder, 1/2 teaspoon onion powder, 1/2 teaspoon kosher salt, 1/4 teaspoon black pepper
Add the chicken back to the skillet.
Bring to a simmer, and cook, stirring often, over low heat for 13 to 15 minutes or until the chicken reaches 165 degrees with an instant read thermometer.
Serve over noodles.