In a bowl, toss the cubed chicken with cornstarch and a pinch of salt until evenly coated.
Heat a large non-stick wok or skillet over medium-high heat with a light coating of cooking spray.
Add the chicken in a single layer and cook for 5-6 minutes until golden brown and crispy. Remove chicken from pan and set aside.
In the same pan, whisk the whole eggs and egg whites together and scramble until just set. Remove and set aside.
Wipe the pan and add the minced garlic, sauteing for 30 seconds until fragrant.
Add the chilled rice, peas, and carrots. Break up any rice clumps and stir-fry for 3 minutes.
Pour in the soy sauce and oyster sauce, tossing the rice until evenly colored.
Return the crispy chicken and scrambled eggs to the pan. Toss for another 2 minutes to incorporate and heat through.
Drizzle with sesame oil and garnish with sliced green onions before serving.