Grate the white soap into a bowl. This might be the longest operation of this recipe.
Chop the colored soap into tiny cubes (1 cm approx.). Pour your grated soap and the minimum quantity of water (80 to 100ml) into the slow cooker or your pan
Turn on the slow cook into high heat and have some water at the ready
Be patient now. Let the mix warm up and mix it with a spoon every now and then. This operation might take 20 to 30 minutes until the soap starts to look like a consistent mixture. The grated soap needs to "melt" into the water.
Add the soap cubes around 20-25 minutes and mix some more. Let the cubes get some heat so they incorporate in the mixture as well.
When the mixture looks like mashed potatoes and the grated soap bits look fully incorporated it's time to add the essential oils. Mix well and now the soap is ready to be poured.
You need to be quick to pour the soap into the mold. As soon as the soap mixture leaves the heat, it starts to harden... Bump the soap mold hard against the countertop several times, to remove any bubbles. Be careful with spilling :)
Let the soap harden for 24 hours, then unmold and cut. Let the soap fully dry for 7 days.