Chop boneless skinless chicken breasts into 1-inch pieces. Toss the chicken with 4 tablespoons of cornstarch until well-coated for a crispy texture.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add coated chicken pieces in a single layer. Cook 5-7 minutes, turning occasionally, until golden brown and cooked through. Remove chicken and set aside.
Add steamed broccoli florets to the same skillet. Sauté for 2-3 minutes to warm and infuse with chicken flavors.
In a small bowl, whisk together honey, ketchup, granulated sugar, brown sugar, white vinegar, soy sauce, and garlic powder. Pour sauce into the skillet with broccoli.
Add cooked chicken back to skillet with broccoli and sauce. Stir to coat chicken evenly.
Mix 2 tablespoons cornstarch with 2 tablespoons cold water to make a slurry. Pour into skillet and stir continuously until sauce thickens, about 2-3 minutes.
Remove skillet from heat. Serve hot, garnished with sesame seeds. Enjoy over rice or noodles for a complete meal.