In a large mixing bowl, add the baking soda, citric acid, cornstarch, and kaolin clay. [I use kaolin clay in bath bombs that use a mold that is not the typical round mold to give them more stability when you pop them from their mold.] Whisk dry ingredients together.
Add in 2/3 cup of the coconut oil. This binds all the ingredients together, so your bath bombs don’t crumble when you touch them! With bombs containing activated charcoal, I use 1/4 cup more than I would in other recipes.
Add polysorbate 80. This helps the coconut oil disperse more evenly in your bath water, makes the bath bombs bubbly and prevents the mica from sticking to the side of the tub.
Melt and add cocoa butter. Add in basil essential oil. Mix well. You may need to use your hands to break down any lumps and make sure everything is mixed in. The mixture is perfect when it holds together when you press it into your hands and feels like wet sand.
Add in 2 tablespoons of the activated charcoal (you may need more to make the mixture a true black as the base is white. When you add more charcoal, you will need to add 1-2 tablespoons of additional coconut oil or it will be too dry)
Add the mixture into each cavity of the muffin mold until the mixture is packed in firmly. Allow to dry a minimum of 24 hours. If these are not 100% dry, they will break when you take them out.
For Whipped Soap
Add whipped soap base, glycerin and polysorbate 80 to mixing bowl. Mix on low speed until fluffy, or about 1 minute. Fold in cornstarch. Mix on low for 30 seconds.
Melt your soap base in microwave-safe bowl in 30-second intervals, stirring after each until melted. Allow to cool for about a minute. Mix in melted melt and pour soap base and fold in cornstarch. Mix on high speed for 1 minute or until the mixture forms peaks, like when you make a meringue. If your frosting is not stiff enough, add a bit more cornstarch and mix in. Repeat until the mixture is nice and firm.
Divide whipped soap into 2 small mixing bowls. Add purple colorant to one bowl and green colorant to the last bowl. Start mixing in 1-2 drops of color. If you want a darker color, add 1-2 more drops and repeat until you get the color you want.
Add purple color frosting to one small piping bag and the green to another. Place large piping tip into a large piping bag. Insert the two small bags into the large bag.
Holding all three bags tightly in your dominant hand and pipe the frosting onto your cupcake bombs. After about 36 hours, the whipped soap will begin to harden. You can drop the bath bomb and soap in the bath together or use separately.
Print the template. I had to enlarge it just a bit, but if you make mini cupcake bombs, you may need to shrink it
You have two options on this step. You can cut out the horns and using a pencil, you can trace onto the foam and then cut the foam. OR you can place the template on the foam and using an X-acto knife, cut out the horns.