Melt butter in a large dutch oven or large pot. Add onions, celery and carrots. Cook for 5 minutes or until softened.
Add flour and cook for 1-2 minutes more.
Stir in chicken stock and half and half. Add cubed chicken and bring pot to a simmer. Add sage and salt and pepper to taste. Cook for 20 minutes.
While soup is cooking, prepare pie crust. Cut into small squares, place on a baking sheet, brush with egg wash and top with finishing salt. Bake as per directions for frozen crust.
Add peas to soup and cook for 2-3 minutes before serving. Serve soup with croutons and enjoy!
Notes
Does this recipe look familiar? It first appeared on my other site, The Brooklyn Cook