Set an oven rack on the center shelf and preheat the oven to 425 degrees F. Line a sheet pan with aluminum foil or parchment.
Place the bacon on a microwave-safe plate lined with a couple layers of paper towels. Top with another layer or two of paper towels, then microwave for around 60 seconds. This will release some (but not all) of the fat. Pat the bacon dry with the paper towels and slice crosswise into 1/2-inch slices.
Toss the brussels sprouts with olive oil and spread in a single layer on the prepared baking sheet. Sprinkle liberally with salt and pepper to taste (see notes). Spread the bacon around the sheet pan.
Roast for 13-15 minutes, then remove from the oven briefly to stir and gently flip the ingredients to make sure they roast evenly on both sides. Sprinkle the garlic around the sheet pan evenly, then return to the oven and roast for an additional 7-10 minutes, until the brussels are deeply caramelized and crisp, and the bacon is fully cooked.
Drizzle with balsamic reduction (or toss with balsamic vinegar), then serve immediately.
Learn more about how to season recipes to taste! It’s an easy yet important skill to learn. I like a lot of pepper, more so than the average person. If you learn to season based on your own personal preferences, you’ll have a lot more control over the outcome!If you don’t want to use balsamic reduction, you can substitute regular balsamic vinegar. Instead of drizzling the syrupy reduction over the veggies at the end, simply toss them with some balsamic vinegar before serving. Since the vinegar is a much thinner consistency, you might use less. Toss the balsamic with the brussels 1-2 tablespoons at a time until the desired flavor is reached.