Preheat your oven to 375°F (190°C). Line a large, rimmed baking sheet with aluminum foil. Create three foil dividers: fold a large piece of foil in half several times to make a sturdy wall for the middle of the pan. Make two smaller walls to divide one half into quarters. This will create one large section (for the turkey and stuffing) and two smaller sections (for the sides).
In a large bowl, combine the bread cubes, onion, celery, 2 minced garlic cloves, chicken stock, eggs, parsley, 1 tablespoon of sage, 2 teaspoons of rosemary, and 2 teaspoons of thyme. Season with salt and pepper. Mix until the bread is moist but not saturated. Let the mixture sit for 15 minutes to absorb the liquid.
Spread the stuffing mixture into the large foil section on your sheet pan. Make a slight indentation in the center where the turkey will sit.
In a small bowl, mix 4 tablespoons of the melted butter with the remaining sage (2 tsp), rosemary (1 tsp), thyme (1 tsp), and 2 minced garlic cloves. Pat the turkey breast dry and season it generously with salt and pepper. Rub the herb butter all over the turkey. Place the turkey in the indentation on top of the stuffing.
Bake the turkey and stuffing for 30 minutes.
While the turkey bakes, prepare the sides. In a medium bowl, toss the sweet potato slices with the remaining 4 tablespoons of melted butter, 1 tablespoon of brown sugar, cinnamon, and a pinch of salt. In another bowl, toss the green beans with olive oil, the remaining 2 minced garlic cloves, salt, and pepper.
After 30 minutes, carefully remove the sheet pan from the oven. Arrange the sweet potato mixture in one of the empty foil sections and the green beans in the other. Top the sweet potatoes with the marshmallows and the remaining 1 tablespoon of brown sugar.
Return the pan to the oven and bake for an additional 30-40 minutes, or until the sweet potatoes are tender, the green beans are cooked, and the turkey reaches an internal temperature of 165°F (74°C) on an instant-read thermometer.
Let the turkey rest for 5-10 minutes before slicing. Serve everything directly from the pan with cranberry sauce on the side.