New England Chicken Pot Pie With Biscuit Crust

Ingredients

• 2 tablespoons butter
• 2 medium onions, diced
• 1 celery rib, diced
• 1 large carrot, diced
• 3 cups cubed (1-inch) cooked chicken
• 1 ½ cups fresh or frozen green peas
• 1 cup diced fresh mushrooms
• Salt
• freshly ground pepper
• ¼ cup vegetable shortening
• ¼ cup all-purpose flour
• 1 ½ cups chicken broth
• 1 cup half-and-half
• 2 cups all-purpose flour
• 1 tablespoon baking powder
• ½ teaspoon salt
• ¼ cup chilled vegetable shortening
• 1 cup whole milk