Slow Cooker Shepherd's Pie

Bahan-bahan (6 porsi)

• 1½ pounds lean ground lamb (or beef)
• 1 large yellow onion (diced)
• 1½ teaspoons salt
• ½ teaspoon black pepper
• 3 cups frozen mixed vegetables
• 4 to 6 cups prepared mashed potatoes (see notes)
• 2 cups beef broth
• 1 packet brown gravy mix
• 2 tablespoons Worcestershire sauce
• 2 tablespoons tomato paste
• 1 teaspoon garlic powder
• ½ teaspoon dried thyme leaves
• 2 tablespoons cornstarch