In a small pan, cook the bacon until crispy. Remove from pan and set aside. Add 1 tablespoon of the butter in the same pan and saute the mushrooms for 1 to 2 minutes. Add the remaining 1 1/2 tablespoons butter and melt. Add the spinach and cook until it is wilted.
Return bacon to the pan and heat through. Adjust seasoning, to taste, with salt and pepper. Keep warm until ready to serve.