Preheat oven to 425°F and grease a large baking sheet with nonstick cooking spray.

Toss the brussels sprouts with olive oil in a mixing bowl until well coated. Spread them out in a single layer on the prepared baking sheet and season with salt and pepper. Roast for 10 minutes, then pull them out.

While the brussels are roasting, combine 4 tablespoons melted butter, 2 tablespoons minced garlic, 1 teaspoon Italian seasoning, 1 teaspoon salt, and 1/2 teaspoon black pepper in a bowl. Add the chicken and toss to coat. If the butter firms up a little because the chicken is cold, don't stress — just toss it well and it'll still do its job.

In a smaller bowl, stir together the remaining 2 tablespoons melted butter, 1 tablespoon minced garlic, 1/2 teaspoon Italian seasoning, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Brush this all over the tops of the roasted brussels sprouts.

Add the seasoned chicken to the pan and return everything to the oven for 10 minutes.

Pull the pan out, cover with shredded cheese, and broil for 3-5 minutes until the cheese is melted and bubbly. Watch it closely — broilers move fast.