Steak and Stilton Pies | Saveur

Ingredients

• 1⁄4 cup olive oil
• 1 1⁄4 lb. beef chuck, cut into 1" cubes
• 2 cloves garlic, finely chopped
• 2 large yellow onions, sliced
• 2 ribs celery, thickly sliced
• 2 small carrots, thickly sliced
• 2 tbsp. minced rosemary
• 1 (12-oz.) bottle stout beer
• 1⁄4 cup flour
• 2 cups beef stock
• 2 tsp. mustard powder
• 1 bay leaf
• 1 tbsp. unsalted butter
• 10 oz. mushrooms, quartered
• 6 oz. English Stilton, crumbled
• 1 (10-oz.) package frozen peas
• 1 (14-oz.) package puff pastry
• 1 egg, lightly beaten