Using a griddle, large saute pan, or wok, add in 2-3 tablespoons of olive oil over medium-high heat. Drain marinade from chicken and add chicken to the pan. Cook 2-3 minutes per side undisturbed until the chicken is cooked through.
Add in 1 tablespoon of garlic and 1 tablespoon butter, saute 30 seconds, tossing with the chicken. Remove chicken and set aside under tented foil.
Add onions, carrots and remaining garlic, saute about 3 minutes then add peas. Cook until everything is soft, about 2 more minutes. Add pepper (no salt). Increase heat to high, add in 3 tablespoons of butter and add in the cold rice, spreading it in an even layer to make surface contact with pan.
Drizzle the soy sauce and sesame oil directly over the rice. Cook rice about 4-5 minutes, stirring occasionally, but allowing rice to sit undisturbed in between stirs to get it crisped and browned.
Scoot rice to the side, add in 1 tablespoon more butter. Add the eggs directly over the butter, add pepper and whisk to cook through. Incorporate the eggs with the rice.
Remove from heat and fold in the cooked chicken and diced mango. This will warm the mango through without turning mushy. Taste the rice and add more soy sauce and sesame oil if needed.