For a bit more flair to your presentation, serve the chicken and rice inside a hollowed-out pineapple. If you can't find chicken thighs, you can use 4 medium chicken breasts, although the meat won't be as tender.
Whisk the pineapple juice, soy sauce, stock, hoisin sauce, brown sugar, garlic and cornstarch together in a medium saucepan. Bring the mixture to a boil and cook until the mixture has reduced to about 1 cup and is the consistency of thick syrup. Set the sauce aside.
Add the oil to a large nonstick skillet and place over medium-high heat. Add the chicken and season it with salt and pepper. Cook, stirring, until the chicken is no longer pink, about 5 minutes. Drain off any liquid, then add the sauce to the skillet and stir until combined. Add the pineapple and cashews if using; cook, stirring, for an additional 1 minute. Serve the chicken on a bed of rice.