Heat oil into a large dutch oven or heavy pot. Saute carrots, onion, celery, and onion until softened, about 5-8 minutes. Reduce heat to low stir in chicken and simmer.
In a separate medium pot, melt butter over medium heat. Whisk in flour, salt, and pepper until smooth. Slowly whisk in chicken broth and half and half until smooth. Increase heat to high while continually whisking until mixture thickens and almost starts to boil. Reduce heat to low and stir in sour cream and peas. Season to taste with salt, pepper and a pinch of garlic salt (won’t need much). Simmer on low while croutons are cooking.
Preheat the oven to 350 degrees F. Gently roll out puff pastry with a rolling pin to even thickness. With a pastry brush, brush pastry with egg wash and lightly sprinkle with Cajun seasoning. With a pizza cutter, cut into ½ inch squares. Place squares onto a large baking sheet lightly sprayed with cooking spray and bake until puffed and golden brown, about 20-25 minutes. Remove and let cool.
Serve in pot pie base in bowls and top with puffy croutons, Enjoy!