First I made these, I actually got four of these slabs by using my silicone mold with dividers.
You can see a picture of the mold here.
Then I made this. I took two of the slabs, they were about one day old, so still a little sticky, and put them in/on the sides of the mold. Then I sprayed the soap and the mold with rubbing alcohol and filled the centre of the mold with soap.
After cutting and trimming the soap, here's what I got. Since it's February I stamped the soap with hearts. Not too bad for the first time trying this.
There's a few tutorials on Pinterest for Side Embed Soap and this is the one I used. Next time I would like my embeds to be thinner so I'll have to pour them in a tray and them cut them to fit the mold.
Let me know if you give it a try and thanks for reading!