Heat the oil or butter in a sauce pot and add the onion, celery and potatoes. Cook, covered, until the potato is just fork tender, about 10-15 minutes.

Stir in the garlic, worcestershire and thyme, cook for 1 minute until fragrant.

Add the ground beef, brown and crumble apart as it cooks. About 3-5 minutes on medium heat.

Pour in the Guinness and turn up the heat but only bring to a low simmer, about 5 minutes uncovered. Stir in the green peas.

Turn to the lowest setting, cook covered while you prepare the pastry dough.

Preheat the oven to 375F.

Meanwhile, roll out the pastry dough and cut into 12 5 inch rounds. Cut 12 rounds into larger circles, about 5.5 inches for easier pie making but this is optional. Feel free to use up any extra dough for smaller pies.

Stir in the cheese until incorporated with the beef.

Spoon filling onto the 5 inch rounds and brush the edges with a little water. Cover with the 5.5 inch round. Press the edges of a fork to seal.

Bake for 12-15 minutes on a baking sheet lined with parchment paper.