Combine olive oil, coconut oil, cocoa butter, castor oil, and shea butter in a large stainless steel pot and melt over medium heat. Remove from heat and allow to cool to 90-100 degrees Fahrenheit.
Weigh lye into a plastic disposable bag. Weigh water in a plastic bowl. Go outside with ingredients and large spoon. Wearing gloves and charcoal mask and long sleeve shirt, add lye to water and stir until lye is dissolved. Allow to cool to 90-100 degrees Fahrenheit.
4.4 ounces lye, 12 ounces water
Prepare 3lb mold by lining with wax paper if needed.
Pour lye water into pot of oils and stir with a hand mixer for 1-3 minutes. Repeat until soap begins to thicken to light trace (See: What is trace). If you are adding peppermint essential oil, now is the time. Stir well.
Separate 1 cup of soap into a separate bowl. Add cocoa powder to larger batch 1 tablespoon at a time until you are happy with the color. Pour cocoa soap into mold.
1-2 tablespoons cocoa powder
Slowly, using a spatula to slow the pour if necessary, pour white soap over the cocoa soap. This is easiest when the soap starts to thicken to medium or thick trace.
Cover and insulate for 24 hours (do not insulate if your house is above 80 degrees). Remove from mold and cut. Allow to cure for 3-6 weeks, until hard.