Preheat the oven to 450 degrees . Arrange the chicken, onions and carrots in an even layer on a foil-lined baking sheet. Toss with the olive oil and season with salt and pepper. Roast, turning the baking sheet halfway through, until the chicken juices run clear when the chicken is pierced, about 35 minutes.
Meanwhile, in a medium saucepan, bring the rice and 1 1/2 cups salted water to a boil. Lower the heat, cover and simmer until the water is absorbed, about 20 minutes. Remove from the heat and let rest, covered, for 5 minutes. Fluff with a fork, then stir in the almonds and parsley; season with salt and pepper. Transfer to a platter, top with the chicken and vegetables and spoon the pan juices on top.