cacao nibs, chocolate (or carob) chips or chunks, chocolate shavings, etc. Or alternatively use shredded coconut or chopped nuts of choice (if not nut-free).
Blend all coconut layer ingredients in a power blender until smooth. Transfer 2/3 of this mixture (leaving the remaining 1/3 behind in the blender) to a 7" x 5" glass container (or any dish of a similar size) that's lined with parchment paper at the base and sides. Even out the layer with the back of a spoon.
Add remaining carob layer ingredients to the blender and blend again until smooth. Transfer this mixture into the container over the coconut layer and smooth out the top. Sprinkle with desired toppings.
Freeze for 5-6 hours or overnight. Thaw out slightly (until you can pull the frozen bar out of the container), pull out of the container onto a cutting board and cut into pieces, and enjoy! Keep leftovers frozen and thaw out a piece at a time as needed for a few minutes for a softer texture.