Heat the oven to 400 degrees Fahrenheit and line a baking sheet with aluminum foil.
Trim the ends off the Brussels sprouts, then slice them in half.
In a large bowl, combine the olive oil, chipotle powder, salt, black pepper, and cayenne powder (optional). Stir to evenly distribute the spices in the oil.
Add the sprouts to the bowl. Mix them with the spiced oil to coat the sprouts.
Evenly distribute the Brussels sprouts across the foil-lined baking sheet, then place the baking sheet in the oven.
Bake for 30 to 40 minutes, or until the sprouts are tender and lightly browned on the edges.
Place the sprouts in a serving bowl. Top with crumbled bacon (optional), then serve.