In a frying pan, heat olive oil over medium heat. Add chopped onions and garlic, sauté until softened (about 5 minutes).
Add ground pork and beef to the pan. Cook until browned, breaking meat apart with a spoon (about 10 minutes).
Stir in thyme, sage, nutmeg, pepper, and salt. Pour in the chicken broth and let simmer for 10 minutes until slightly thickened. Remove from heat and let cool.
Preheat the oven to 190°C (375°F). Roll out half of the pie pastry to fit the pie dish. Fill it with the cooled meat mixture. Roll out the second half to create the top crust, pressing edges to seal.
Make a few slits in the top crust for steam to escape. Beat the egg and brush it over the crust for a golden finish.
Bake in the oven for 25-30 minutes, or until the crust is golden brown and filling is bubbling.
Allow the pie to rest for 15 minutes before slicing. Serve warm with lemon wedges and garnish with fresh parsley if desired.
