In a small saucepan, combine the grated soap and the water. Bring to a low simmer and whisk constantly until the soap has just melted. Add the glycerin and whisk again.
Pour the soap mixture into a plastic container or heat-proof bowl (if using plastic, make sure it's not so hot it can melt your container—let the mixture cool slightly first if needed) and let it cool to just slightly above room temperature. You want your soap to be cool to the touch but not solid. If it hardens, microwave it in 10-second intervals until it melts again.
Combine the coconut oil and vegetable shortening in a large bowl. Use an electric mixer to whip the oils until smooth and the consistency of frosting (you can put the bowl in the freezer for several minutes to help the oils firm up).
Slowly pour your room temperature soap mixture into the bowl of whipped oils. Whip until fluffy.
Add grapeseed oil, essential oils, and beet root powder for color. Whip until combined.