Add chopped bacon to medium skillet. Cook on medium heat until about 1/2 way done. (do not drain bacon drippings).

Add brussel sprouts that have been cut in half (and de-stemmed). Continue to pan-sear brussel sprouts in bacon drippings for a couple minutes (add a tiny bit of olive oil to skillet only if necessary). Lightly season brussel sprouts with salt and pepper.

Continue cooking until brussel sprouts begin to soften (3-4 minutes), flipping over half way through cooking. Add 3 Tablespoons water to skillet; cook until water has cooked away.

Add sliced mushrooms and shallots to skillet. Continue cooking until mushrooms are done and cooked through (approx. 3-4 minutes). Add minced garlic; cook for additional minute. At this point, brussel sprouts and mushrooms should be cooked through. Add butter, and stir until butter has melted and coated veggies. (Note: Butter is completely optional, but adds good flavor)

Remove pan from heat, season with additional salt and pepper (if needed), then serve.