Line a 6-quart slow cooker with a liner if using one. Liners are preferred for easy cleanup.

Drizzle olive oil over the bottom of the liner or slow cooker.

To a large, gallon-sized ziptop plastic bag, add the chicken, cornstarch, salt, and pepper. Seal the bag and toss to coat the chicken evenly. Add the coated chicken to the slow cooker, distributing it evenly. Set aside.

In a medium bowl, combine the coconut milk, peanut butter, soy sauce, honey, rice wine vinegar, lime juice, sesame oil, ginger, garlic powder, and optional cayenne pepper. Whisk until well combined. Tip: If your peanut butter is resistant to smoothing out, place the bowl in the microwave and heat on high power for 30-second bursts, ensuring the bowl is microwave-safe.

Pour the sauce mixture over the chicken in the slow cooker. Use a spoon to distribute the sauce if necessary, ensuring all chicken pieces are coated. The sauce will appear to be a lot, but it reduces by at least half during cooking.

Cook covered on high for about 2 hours or on low for about 4 hours. If cooking on high, start checking at 90 minutes. If cooking on low, start checking at 3 hours. Slow cookers vary, so cook until the chicken is done (reaches 165°F on an instant-read thermometer).

Serve the chicken hot, spooning extra cooking sauce over the top as desired. Garnish with chopped peanuts, optional cilantro, and optional green onions.