Chicken a la King

Bahan-bahan (4 porsi)

• ½ cup butter (unsalted )
• 8 ounces white mushrooms (sliced)
• 1 small yellow onion (diced)
• 1 teaspoon garlic powder
• ½ teaspoon black pepper
• ½ teaspoon kosher salt (or to taste)
• ½ cup all-purpose flour
• 2 cups chicken stock
• 1 cup half and half
• 1 cup frozen petite peas
• ½ cup pimentos (drained and chopped )
• 3 cups cooked shredded chicken (or shredded rotisserie chicken)