Preheat the oven to 350°F. Spray a 9 or 10 inch deep dish pie pan with cooking spray. Set aside.
In a large skillet, cook the bacon over medium-high heat until crisp. Remove with a slotted spoon to paper towels to drain.
To the drippings add onion. Cook for 3 minutes or until softened and beginning to brown. Add garlic. Cook for 1 minute longer. Remove from heat adding bacon and spinach to the pan. Mix well.
To assemble: Sprinkle 1 cup cheese on bottom of pie dish. Arrange spinach and bacon mixture evenly on top.
In a medium mixing bowl or using a stand blender, whisk together half and half, eggs, pepper, salt, paprika, mustard and nutmeg until fully blended. Add Parmesan, mix well.
Pour egg custard evenly over spinach. Use a knife to gently move the filling around to make sure the custard is evenly distributed. Top with remaining cheese.
Bake for 50-60 minutes or until the center is set when gently shaken.
Cool on cooling rack for 30-45 minutes before cutting.