Anyone have any good recipes or add ins for plain vanilla bettercreme so that I can turn it into a mocha filling? tia!

Not sure about bettercreme specifically, as I've never used it, but to make mocha buttercream, I use the International Foods powdered mocha drink mix. I mix a few tablespoons with just enough hot water to make a paste (about the consistency of toothpaste) and add that to the buttercream.