Brown beef and pork with onion and garlic in a large skillet. Drain and stir in 3/4 cup water, celery, carrot, bouillon and bay leaf. Simmer for 10 minutes over medium heat; remove from heat and discard bay leaf.
Preheat oven to 350 degrees F (175 degrees C).
Stir potato, pepper, cinnamon, cloves and nutmeg into skillet mixture, then spoon mixture into deep dish pie shell. In a small bowl combine egg yolk and 1 tablespoon water to make egg wash; brush edge of crust with wash, then carefully add top crust and seal edges. Make several slits in top crust; brush with remaining egg mixture.
Bake in preheated oven for 45 minutes, or until golden brown.