I looked in the recipes section and didn't find one. I have been using the Wilton butter cake recipe (which is YUMMY) and modifying it by adding 4 oz of melted semisweet chocolate to part of the batter and then marbling it in the pan. But for some reason it always turns out a little dry, even though the original butter cake never does. Does anyone have suggestions?
Thanks!

That's unusual. I've always done the same thing and never had issues.

I'll reserve 1/3 of the batter and add Hershey's syrup to it. Maybe 1/4 cup of syrup.

Chocolate cake does bake differently than non-chocolate cake. Have you tried reducing the temperature to see if that might help?

Make your favorite chocolate and fav yellow and blend.
put yellow in the pan add dallops of chocolate and blend with spoon a bit until marbled.