In a large bowl, combine the cornstarch, baking soda, and Epsom salt. Mix well and set aside.

In a small bowl, add the essential oil drops to the carrier oil and stir to combine.

Slowly drizzle the oil mixture into the dry ingredients, mixing continuously. The mixture should resemble damp moon sand and hold together when squeezed. If it feels too dry, add additional carrier oil one teaspoon at a time.

Once the texture is right, gently mix in the citric acid.

Add cocoa powder a little at a time, mixing until you reach your desired color.

Pack the mixture tightly into both halves of the bath bomb mold, slightly overfilling each side. Press the two halves together firmly and twist until the mold edges touch.

Carefully remove one side of the mold, then the other, and place the bath bomb on a flat surface.

Allow the bath bombs to dry undisturbed for at least 24 hours, or until fully hardened. If they feel crumbly, let them sit longer.

Once dry, melt a small amount of cocoa butter with a teaspoon of cocoa powder. Let it cool for a few minutes, then drizzle over the tops of the bath bombs.

Sprinkle dried rose petals on top before the drizzle sets.