Preheat oven to 350 degrees F (180 degrees C). In a saute pan over medium high heat, brown the Bacon (6 slice) pieces until crisp, 8 to 10 minutes.
Remove bacon from the pan, and reserve the grease. Add the Onion (3/4 cup) and saute for 2 minutes.
Add the Shiitake Mushroom (6 ounce) and cook for 4 minutes until browned.
Add Arugula (8 ounce) and cook until wilted, just a minute.
Add the bacon back to the pan and combine.
In a large bowl, add the Egg (12), Heavy Cream (1/2 cup) and three-quarters of the Emmental Cheese (1 cup) and whisk together. Season with Salt and Pepper (to taste).
Pour the egg mixture over the ingredients in the pan. Let cook over medium heat for 5 minutes until the edges begin to come together.
Place in the oven for 20 to 25 minutes.
Remove from oven and add the remaining cheese over the top. Serve and enjoy!