Add the bacon to the skillet over medium heat and cook until your desired crispness. Remove from the pan and set aside. Keep the bacon fat because you will cook the remainder of the ingredients in this fat for extra flavor. Chop the bacon into pieces to sprinkle over the Brussels sprouts after they are done cooking. 

Add the shallots to the bacon fat and cook for 2-3 minutes or until translucent. Add in the garlic and cook until fragrant, this will only take about a minute. 

Add the Brussels Sprouts to the skillet and mix them around to evenly coat with the bacon fat and mix the shallots and garlic in. 

Try to add them to a single layer with the cut sides down as much as possible. This doesn't need to be perfect, but it will help you get crispy brown edges. Turn the heat up to medium-high heat to crisp up the edges. 

Leave them undisturbed for a few minutes, and then mix them around to ensure even cooking. Cook them until they are golden brown and can be pierced with a fork, about 15 minutes. If they are browning too quickly reduce the heat back down to medium.

Remove the skillet from the heat and sprinkle cooked bacon on top.

Serve immediately and enjoy!