Gather all ingredients.

Combine beef stew meat, ale, and onion in a large saucepan over low heat; simmer until beef is tender, about 30 minutes. Preheat the oven to 400 degrees F (200 degrees C).

Season beef mixture with Worcestershire sauce, garlic, parsley, thyme, salt, and black pepper; add potatoes and mushrooms. Increase heat to medium; cover saucepan and simmer until potatoes are just fork-tender, 10 to 15 minutes.

Whisk a small amount of sauce with flour in a small bowl; stir into beef mixture. Simmer until slightly thickened.

Place 1 pie crust into bottom and up sides of a 9-inch pie plate. Spoon hot beef mixture into crust; top with remaining pie crust. Cut slits in top crust to vent steam; crimp edges to seal together.

Bake in the preheated oven until crust is golden brown and gravy is bubbling, 35 to 40 minutes.