Tourtière (French-Canadian Christmas Meat Pie)

Ingredients

• Pastry for a 9-inch double-crust pie, chilled
• 1 lb ground pork
• 1/2 lb ground beef
• 1 onion finely diced
• 2 clove garlic
• 1 medium russet potato boiled and mashed
• 3/4 cup beef broth
• 1 tsp salt
• 1/2 tsp pepper
• 1/2 tsp cinnamon
• 1/4 tsp ground cloves
• 1/4 tsp allspice
• 1/2 tsp dried savory or thyme
• 1 egg beaten with 1 tbsp water