Brussels Sprout Salad with Chicken and Warm Bacon Vinaigrette

In a medium skillet over medium heat, cook bacon until crispy, 6 minutes, then transfer to a paper towel-lined plate. Add garlic and shallots to skillet and cook until softened, about 2 minutes. Whisk in vinegar and mustard and season generously with salt and pepper. (If there isn't enough bacon drippings to create a dressing, whisk in 1 tablespoon olive oil.) Keep warm. In a large skillet over medium-high heat, heat olive oil. Season chicken with salt and pepper and sear until golden brown and juices run clear, about 5 minutes per side. Remove from heat and let chicken rest covered in foil. In a large mixing bowl, toss Brussels sprouts, parsley, and croutons with warm dressing. Serve with chicken and top with additional dressing and bacon.