Melt 1 1/2 Tbsp butter in a large soup pot over medium heat. Add diced onions and cook for 4-5 minutes, or till onion is tender. Add celery, carrots, potatoes, water, chicken base, seasonings, and salt and pepper. Simmer till vegetables are tender, about 15 minutes.
Meanwhile, roll out pie crust and cut into strips. Place on a large cookie sheet and bake at 425° for 10-12 minutes or till lightly browned and crispy. Set aside.
In a medium sized saucepan, melt the 1/4 cup butter over medium heat. Whisk in the flour, then the milk and cream. Cook and stir till mixture bubbles and thickens. Let boil at least one minute, stirring constantly. Add to the vegetables and broth.
Stir in the shredded chicken and frozen peas. Heat through and serve with pie crust strips.