Slice up your mushrooms, and dice up your onion. Heat fat of your choice in a large skillet (I used a couple tablespoons of grass-fed butter), and add mushrooms and onion. Saute for a few minutes, until the onions are opaque, then set aside.
Slice up the bacon, and cook in a skillet until done. Place on a plate with paper towels to drain.
Cook the ground sausage in the pan until it is cooked through, and place on a plate with paper towels to drain.
Crack your eggs into a large bowl along with salt and pepper (I used 1 tsp salt, 1 tsp pepper and 1 tsp red-pepper flakes) and whisk until all the eggs are beaten.
Grease an 8x8 casserole dish, and place the onions and mushrooms into the dish. Add the sausage and mix everything up until it all looks evenly distributed.
Sprinkle your bacon in a layer on top of that.
Then, pour the eggs slowly over the whole casserole, making sure to distribute evenly.
Bake in heated oven for 30-35 minutes, until eggs are cooked through. Remove from oven and let it cool for about 10-15 minutes before serving. Serve and enjoy!