Fill a large pot 3/4 of the way with water and add 1 teaspoon of salt and the Brussels sprouts. Put the pot over high heat and bring to a boil. Let boil until the Brussels sprouts are just fork tender about, 8 to 10 minutes. Remove from the heat, drain the sprouts and transfer to an ice bath. Let cool completely, then drain and set aside.
Cut the Brussels sprouts into 1/4-inch lengthwise slices and set aside. Add the bacon to a medium saute pan, and cook until just crisp, then remove to a paper towel lined plate to drain. Adjust heat to medium-high, add the onions to the pan and saute until they are translucent and just beginning to caramelize, about 5 or 6 minutes. Add the butter to the pan, then add the Brussels sprouts and saute for 3 to 4 more minutes. Season with the remaining 1 teaspoon of salt and 1 teaspoon of pepper. Transfer to a serving bowl or platter and sprinkle with the reserved bacon and the cheese. Serve immediately.