Preheat the oven to 350 degrees F. Brush a baking dish with 1 tablespoon of the butter. Slice a little bit of the flesh from the bottom of each peach half so they sit evenly in the baking dish. Scoop a tiny bit from the center, so the pit space is a little larger. Put the peaches in the dish, cut-side up.
Whisk together the remaining 4 tablespoons butter, honey and black pepper in a small bowl and pour it evenly over the peaches. Roast the peaches until lightly golden brown and just soft, about 25 minutes.