Heat oil in a large skillet or Dutch oven. Add onions, carrots, celery and sauté until tender 5-7 minutes.
Add mushrooms and garlic and continue cooking for 5 more minutes.
Sprinkle flour over vegetables and stir until the flour is incorporated. Slowly add almond milk and veggie broth. Stir until the broth begins to thicken.
Add soy sauce, miso paste (if using), Italian seasoning, salt, pepper, and peas.
Pour pot pie filling into an oven-safe baking dish. Lay pie crust on pot pie filling. Trim edge of pie crust so that it is about 1.5” wider than diameter of baking dish.
Fold pie crust edge and crimp all around the edge of the pot pie. Cut slits into pie crust to let steam escape.
Brush pie crust with egg wash and bake until the crust is golden brown.
Optional: Remove pot pie from oven and brush crust with a little more egg wash. Then, sprinkle with sea salt and fresh thyme leaves. Bake for 3 more minutes.