This is my go to favorite chocolate cake recipe (minus the icing, which I'm sure is good.but not the point) - "Ultimate Chocolate Cake". It has the 2 things I think are key to a perfect chocolate cake - coffee and sour cream!
I used this filling but it was too thick to strain as the recipe suggests. I may try adding an extra to half cup of milk next time. It might also be a good idea to double the filling because I used it in a large flan pan.