Microwaving Ivory soap is a fun project that won't hurt your microwave, but it will make your whole house smell soapy clean. Step 1. Place on a microwave safe plate in the center of the oven. Step 2. Cook the bar of soap on HIGH for 2 minutes. Don't take your eyes off the bar of soap as it begins to expand and erupt into beautiful puffy clouds. Be careful not to overcook your soap souffle.