Chocolate theme bridal shower cake?

I have been trying to find a chocolate themed bridal shower cake without any luck. The bride really likes the hershey brownie from texas steakhouse, it's a brownie with a chocolate bar melted on top. I was thinking of doing this but with a cake and using white icing to write on it. But, I will have to make the cake a couple days before the shower so how do I make sure the chocolate is melted slightly. I want to be able to still make out the candy bar so I don't want it completely melted. Texas Steakhouse probably just puts the chocolate on top while the brownie is still warm. Any suggestions would be great. I'm also open to different cake ideas. Thanks