In a large skillet over medium heat, cook the bacon until crisp & browned on both sides, about 7-10 minutes. Remove and place on paper towels to drain. Remove all but 2 teaspoons of bacon grease.
Add the olive oil to the pan. Once hot, add the mushrooms and onions, and cook, stirring often, until softened and lightly golden, about 10 minutes.
Add the minced garlic and stir constantly for 60 seconds.
Add the spinach and cook, stirring frequently, until wilted, about 2 minutes.
Season with sea salt and freshly cracked black pepper to taste, and serve immediately. Enjoy.