Preheat oven to 400 degrees
Heat skillet over medium high heat.
Add 2 tbsp extra virgin olive oil.
Add chicken to skillet and season with 1 tsp salt and 1/2 tsp black pepper.
Cook 8-12 minutes until chicken is browned and cooked through.
Add shallots and onion to skillet and stir, cooking till translucent, an additional 2-3 minutes.
Add peas, carrots and potatoes to skillet and cook for a few minutes until veggies start to soften.
Add butter to skillet and let it melt. Sprinkle in flour and stir to combine. Cook for 2-3 minutes, stirring constantly.
Add chicken broth, and stir till combine. Cook for an additional 3-5 minutes, or until mixture has started to thicken up.
Season with reaming salt and pepper. Add fresh herbs, mustard, and creole seasoning.
Once pot pie mixture has reached desired thickness, taste and adjust seasoning as needed.
Turn off heat to pot pie mixture and allow to cool for at least 10 minutes.
While pot pie mixture is cooling, Roll out puff pastry on lightly floured surface.
Take rolled out puff pastry and lay it over top of cooled pot pie mixture. Trim off any excess crust.
Brush top of crust with beaten egg mixture.
Bake at 400 degrees for 30 minutes until crust is deeply browned and mixture is bubbling.
Remove from oven and allow pot pie to cool for 10-15 minutes before serving.