Preheat the oven to 450°F.

Cook the spaghetti according to the package. Drain and rinse with cold water to stop it from cooking.

Season the chicken on both sides with salt and pepper. In a cast iron pan, heat one tablespoon of olive oil over medium heat. When hot, swirl to coat the entire pan. Add the chicken and cook for 4 minutes. Flip and immediately place in the oven. Cook for about 9-10 minutes, or until an internal temperature reads 165°F.

Meanwhile, in a small measuring cup or bowl, whisk together the balsamic vinegar, Dijon mustard, and brown sugar. Set aside.

When the chicken is almost ready, toss the pasta with the pesto and heat in the original pot until warmed through over medium heat.

Plate the chicken and top with two slices of mozzarella, the tomatoes, and fresh basil. Drizzle with the balsamic vinegar mix. Plate the pasta and sprinkle freshly grated Parmesan on top.

Serve immediately. Enjoy!