It's been a while since I've soaped with purees. I've used avocado, pumpkin and carrot purees, but haven't yet tried banana. It was last year when I saw a tutorial from Cee Gee (Oil & Butter blog) on how to make banana milk, and I made a note to try this someday. It's basically the same technique I use to puree, but instead of using distilled water (or I've also used baby food), you use milk instead. The link to Cee's tutorial is here on how to make it...thanks, Cee!
I made the soap a little bit differently...used equal parts goat milk
and banana to make the banana milk, as in the tutorial...but after
stickblending, I didn't put the banana milk into the freezer. Instead, I
went with the split method, where I used part water for the lye
solution and then stickblended the banana milk into the oils before
adding the lye water. This was not 50/50 either...more like 70/30. The
soap has discolored to a deep, rich brown from the goat milk and
the honey fragrance, which has some vanilla content. I can't get over the speckles...love 'em!