Preheat the oven to 450°F. Remove discolored leaves from Brussels sprouts, trim the ends, and cut in half or quarters depending on their size. Place them on a parchment paper lined baking sheet. Drizzle olive oil over them and toss to coat evenly. Season with salt and pepper.
Roast for 15-20 minutes until browned and somewhat charred. Remove from the oven.
While the Brussels sprouts roast, heat 1 Tablespoon of olive oil in a large skillet over medium heat. Add the pancetta and shallots and cook, stirring often, for 8-10 minutes, until browned and crispy. Use a slotted spoon to remove them to a plate.
Add the pecans to the remaining oil, reduce the heat to low, and cook, for 2-3 minutes, until browned. Be sure to stir often.
When the Brussels sprouts are done, transfer them to a serving bowl and add the pancetta and shallots. Sprinkle the pecans on top and serve immediately.