In a large skillet over medium-high heat, add butter.
Once melt, add onions, carrots, celery, and garlic. Cook for about 5-7 minutes or until tender.
Add in flour, salt, pepper, thyme, parsley, chicken broth, heavy cream, and optional cajun seasoning. Whisk until there are no lumps.
Turn the heat to medium-low and simmer for 5 minutes.
Add crawfish tails, mix with the vegetables. Cover and simmer for another 3-5 minutes or until the crawfish meat just turns opaque. (If you use pre-cooked crawfish tails, you can simply add the crawfish tails together with the frozen peas).
Stir in frozen peas. Mix well. Remove from heat and set aside.
Preheat oven to 400°F.
Remove the pie dough from the refrigerator. On a clean surface dusted with flour, roll each dough disk into a 12-inch circle.
Place one crust into a 9-inch pie pan. Trim the overhang of dough with a knife and discard.
Spoon the crawfish pie filling on top of the bottom crust.
Cover the filling with the second crust. Trim the extra overhang off the sides.
Seal the edges by crimping the pie crusts together.
Use a sharp pairing knife to cut several small slits in the top crust to allow steam to escape.
Brush the top of the curst with egg wash.
Bake for 30-40 minutes or until the crust turns golden brown.
Allow it to cool for 10-15 minutes before cutting into slices. Serve and enjoy!