I love this peanut butter mousse filling recipe:
but it's consistency worries me because it's kind of like building a house on pudding! Do you think it would work to add more powdered sugar or reduce the cream to thicken it up some?
Probably either or would work. If you haven't already made it, try this recipe: http://cakecentral.com/recipes/2316/peant-butter-cup-filling. I've made it twice now and have gotten rave reviews. I use a little more powdered sugar than it requires and then let it sit for about twenty minutes and it's good to go.
I just made and used this recipe for a cake last weekend. I hear ya about the consistency...it was like loose pudding. But I piped a dam of stiff bc and it held nicely. The taste is phenomenal! (Especially with dark chocolate cake!!!)