I would be really hesitant to make something intensely chocolate using splenda, it just doesn't work. I just made some fudge which used a lot of Erythritol and less splenda but that also wasn't real great.

Awhile back what I did was make a chocolate flourless cake and I used bittersweet chocolate and replaced the small amount of added sugar with splenda and E. That worked out just fine. But it wouldn't have worked if the chocolate hadn't had sugar in it. It was "lower carb" but definitely not low carb.

At the moment I just don't trust that I can make a heavily chocolate dessert, so I avoid them. Someday there will be a sweetener that work well with chocolate but for today I am just going to avoid trying to make chocolate anything. If you don't use much chocolate, just a little, this isn't such a bit problem. But in anything that a high % of chocolate, you will have this challenge.

I was going to take chocolate peanut butter low carb fudge to a party tonight but it tasted low carb... so instead I'm making lemon/berry bars and taking them instead. No issues with sweeteners adding odd tastes.