Preheat the oven to 425°F. Fit pie crust into pie dish. Set aside.
Cook bacon in a medium sized skillet until crispy, then remove from the pan to drain on paper towels. Discard all but 2 tablespoons of the bacon drippings from the pan.
Add sliced onion to the bacon drippings. Season with salt and black pepper to your taste. Cook on medium-low for 20 minutes or until golden.
To assemble: Arrange the onions over the crust, and sprinkle the bacon on top.
Sprinkle the bacon with cheese.
In a medium mixing bowl, whisk together heavy cream, eggs, Parmesan cheese, chopped parsley, salt, garlic powder, thyme, paprika and dry mustard until fully combined. Pour the filling over the cheese.
Bake for 15 minutes at 425°F then lower the oven temperature to 400°F. Continue to bake for an additional 15 minutes or until the top is golden and the filling is set when gently shaken. Cover the edges with foil if needed, to prevent over baking.
Allow to rest on counter for at least 30 minutes before cutting.
Serve warm or at room temperature.