Remove tough outer layers from lemongrass. Finely grate bottom third of 1 stalk. Set aside. Discard rest of stalk. Trim and discard top third of remaining stalk. Bruise stalk, to help release oils, by whacking it a few times against a cutting board. Tie stalk in loose knot. Set aside. Place grated lemongrass, shallot, garlic, ginger, red pepper flakes, turmeric, and water in food processor. Process, adding a bit more water if necessary, until paste forms. Heat oil in large skillet over medium heat. Season chicken with salt and pepper. Add to skillet. Cook, turning once, until lightly browned on each side, 8 to 10 minutes. Transfer to plate. Set aside. Cook spice paste in same skillet, stirring, until fragrant, about 5 minutes (paste will begin to darken as it begins to fry). Add cinnamon, cardamom, star anise, coconut milk, sugar, and knotted lemongrass to skillet. Bring to simmer. Add chicken, turning pieces occasionally and scraping bottom of skillet often, until chicken is cooked through and coconut milk has broken (fat will separate from liquid and start to brown chicken further), about 60 to 90 minutes. Meanwhile, toast coconut in dry small skillet over medium heat, tossing occasionally, until golden brown, about 5 minutes. Cool. Arrange chicken on platter. Spoon any cooking liquid over chicken. Top with coconut, cilantro, and chives. Serves 4–6.