Step 1: Prepare the Beef Filling

1. Heat olive oil in a large skillet or Dutch oven over medium heat.
2. Add beef stew meat, season with salt and black pepper, and brown on all sides (about 5 minutes). Remove and set aside.
3. In the same pan, sauté onions, garlic, carrots, and celery until softened (about 5 minutes).
4. Stir in mushrooms (if using), potatoes, tomato paste, Worcestershire sauce, thyme, and rosemary. Cook for 2 minutes.
5. Sprinkle in flour, stirring well to coat the vegetables.
6. Gradually add beef broth and red wine, scraping up any browned bits.
7. Return the beef to the pot, bring to a simmer, and cook for 20-25 minutes until the beef is tender and the sauce has thickened.
8. Stir in frozen peas and adjust seasoning as needed.

Step 2: Prepare the Pie Crust

1. In a large bowl, whisk together flour and salt.
2. Cut in butter using a pastry cutter or fork until the mixture resembles coarse crumbs.
3. Gradually add ice-cold water, mixing until the dough comes together.
4. Divide the dough into two discs, wrap in plastic, and refrigerate for 30 minutes.

Step 3: Assemble the Pot Pie

1. Preheat oven to 400°F (200°C).
2. Roll out one pie crust and fit it into a 9-inch pie dish.
3. Pour the beef filling into the crust, spreading it evenly.
4. Roll out the second pie crust and place it over the filling.
5. Seal and crimp the edges, then cut small slits on top to allow steam to escape.
6. Brush with egg wash for a golden crust.

Step 4: Bake the Pot Pie

1. Bake for 35-40 minutes, or until the crust is golden brown.
2. Let it rest for 10 minutes before slicing.
3. Garnish with fresh parsley and serve warm.