Proper Cottage Pie — Britain's Ultimate Comfort Casserole | CookNoted

Ingredients

• 2 lb ground beef, preferably 85/15 blend
• 1 large large yellow onion, diced
• 2 medium medium carrots, diced small
• 1 cup frozen peas (no need to thaw)
• 2 tbsp tomato paste
• 1 cup good-quality beef broth
• 2 tbsp Worcestershire sauce
• 1 tsp dried thyme
• 2 tbsp all-purpose flour
• salt and black pepper
• 3 lb russet potatoes, peeled and quartered
• 4 tbsp unsalted butter
• 0.5 cup whole milk, warmed
• 1 large large egg yolk, beaten
• salt