In a saucepan, melt the butter over medium heat. Add the millet and toast until golden and beginning to pop, about 5 minutes. Stir in 2 cups hot water, the cinnamon stick and salt and bring to a boil. Lower the heat, cover and simmer until the grains are tender and most of the liquid is absorbed, about 12 minutes.
Stir in the half-and-half, dried cherries, brown sugar and cardamom, then increase the heat to medium and cook until heated through, 2 to 3 minutes. Discard the cinnamon stick before serving.