Add peanut butter, coconut milk, lime juice, soy sauce, brown sugar, ginger, garlic, and red pepper flakes to medium bowl. Whisk well until ingredients are fully combined.

Transfer 1 cup of prepared sauce to small bowl and cover with lid or plastic wrap, then place in refrigerator and chill until ready to serve. Set remaining sauce aside.

Place chicken pieces in baking dish. Cover with remaining peanut sauce, then toss or stir chicken to coat well. Cover dish with plastic wrap and refrigerate at least 1 hour, up to 8 hours max. Toss or stir chicken again at least once during marinating time.

After chicken has marinated for desired length of time, remove dish from fridge and uncover. Thread marinated chicken pieces onto skewers if using, then place on lightly-greased baking sheet. If not using skewers, fit baking sheet with wire baking rack and place chicken pieces on top of rack.

Preheat broiler to high. When preheated, place baking sheet with chicken under broiler. Broil chicken 6 minutes or until internal temperature reaches 160° Fahrenheit.

While chicken cooks, remove refrigerated sauce from fridge and bring to room temperature.

When chicken reaches 160° Fahrenheit according to internal meat thermometer, carefully remove skewers from under broiler and let rest 5 minutes before serving. Serve grilled chicken with desired sides, garnishes, and room temperature peanut sauce.

Preheat grill to medium-high heat, approximately 375° to 450° Fahrenheit. Lightly spray grill grate with cooking spray (optional).

When grill reaches desired temperature, place chicken skewers directly on grill grates, over indirect heat, and close grill lid. Grill chicken 6 minutes, then flip chicken and grill another 6 to 10 minutes. Chicken is ready when it reaches 160° Fahrenheit internally and releases from grates easily.

While chicken cooks, remove refrigerated sauce from fridge and bring to room temperature.

When chicken is ready, carefully remove skewers from grill and let rest 5 minutes before serving. Serve grilled chicken with desired sides, garnishes, and room temperature peanut sauce.