Preheat the oven to 375°F (190°C).
In a large skillet, melt the butter over medium heat. Add the sliced onions and cook until caramelized, stirring occasionally, for about 15-20 minutes. Remove from heat and set aside.
In a medium bowl, whisk together the eggs, heavy cream, salt, black pepper, dried thyme, dried oregano, dried basil, and dried parsley.
Place the pie crust in a 9-inch (23 cm) pie dish. Sprinkle the diced cooked pork evenly over the crust. Spread the caramelized onions on top of the pork. Pour the egg mixture over the onions.
Sprinkle the shredded cheddar cheese over the top.
Bake in the preheated oven for 35-40 minutes, or until the quiche is set and the crust is golden brown.
Allow the quiche to cool for a few minutes before serving. Enjoy!