Rub 1 teaspoon salt and 1/2 teaspoon pepper around the whole turkey breast, in every crevasse and crevice. Gently peel back the skin and rub the seasoning under the skin too. Do the same with the honey, concentrating it under the skin; avoid putting the honey on top of the skin.
On a baking sheet, mix the thyme, carrots, sweet potatoes, fennel, onions and 2 tablespoons of the melted butter. Season with salt and pepper. Spread the vegetables out evenly and place the turkey on top of the vegetables. Next, brush the remaining 2 tablespoons melted butter all over the turkey and on top of the skin.
Cook for 15 minutes, then bump the temperature down to 325 degrees F and cook until the meat registers 165 degrees F on a GOOD instant-read thermometer, for another hour or so. Let rest at least 10 minutes.
Slice and serve with the roasted vegetables. The turkey will keep in the fridge for up to 5 days, and is perfect for the kids' lunches the following week.