In a medium saucepan, whisk together the pineapple juice, soy sauce, chicken stock, hoisin sauce, brown sugar, garlic and cornstarch. 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 olive oil to a large nonstick skillet set over medium-high heat. Add the chicken to the pan and season it with salt and pepper. Cook the chicken, stirring, until it is no longer pink, about 5 minutes. Drain off any liquids then add the sauce to the pan and stir until combined. Add the pineapple and cashews and cook, stirring, for an additional 1 minute.
Serve the chicken atop a bed of rice
