First of all welcome to the LC Forum! It's a great group of folks here with lots of support and advice. We also work in the odd giggle or snicker - and I don't mean the candy bar.
Splenda can't be used as a replacement for sugar in most candy making. It does not crystalize at all. I guess the sugared walnuts are no-go for you. (It
is possible to make this stuff and not sample, you know.

) You might also check the Splenda recipes on the box or their website for other recipes.