In a medium-sized skillet or wok over medium high heat add olive oil and chicken. Brown until almost cooked through and add zucchini, bell pepper, mushrooms, carrots, and snow peas. Cook until veggies are tender and chicken is no longer pink. Add cashews.
Add chicken broth, soy sauce, garlic, brown sugar, and sesame oil to the pan. In a small bowl whisk together cornstarch and water to make a slurry. Pour into pan and stir until incorporated. Let simmer for 2 minutes or until sauce has thickened.
Garnish with green onions and serve over rice if desired.