Begin with the balsamic glaze by pouring balsamic vinegar into a small sauce pan over high heat. Bring to a boil and reduce to medium-medium high to simmer. Stir occasionally until sauce has reached desired thickness. This took me about 30 minutes for a very syrupy glaze. 20-30 minutes should be all you need. Once desired consistency is reached, remove from heat immediately.
Fill a medium sauce pan half way with water. Bring to a boil. Add brussels sprouts and cook for just 2-3 minutes. Strain and remove. This step helps soften the brussels sprouts–if you like them crunchier, feel free to skip it.
Heat olive oil in a large pan over medium heat. Set aside any extra leaves that fall off your brussels sprouts–you'll use those later (they cook faster). Add brussels sprouts flat side down. Season with a generous pinch each of salt and pepper. Cook until seared and brown, about 5-7 minutes. Flip brussels sprouts and move them all to one side of your pan.
Add bacon to the other side of the pan and cook until it begins to crisp, about 5 minutes. Add dates and extra brussels sprouts leaves. Toss to combine. Continue cooking for an additional 5 minutes.
At the very last moment, add chopped apple and give a quick toss. Remove from heat. Serve topped with balsamic vinegar if desired. This dish is best served immediately, but leftovers can be stored in the refrigerator in an airtight container for up to 5 days.