Add carrots, butter, salt, and pepper to a 2-quart or larger pot. Add 1 cup water and bring to a boil over high heat. Stir, cover pot, reduce heat to low, and cook for 20 minutes. Remove lid and stir. If a lot of water remains, increase heat to medium-high and continue to cook until most liquid has evaporated and carrots are fork-tender and sweet, 8 to 10 minutes longer. Drain and serve.