My favorite candy bar has always been Fifth Avenue so while wanting to create something I wanted to eat on a cake this came to mind I used a cake mix on this one and it is very good. I also took the extra mix and made cupcakes which is equally as good.
I use 2 cake mixes so I can have full layer and level the cake. But only mix one mix at a time accoriding to the directions when finish beating add 1 cup of chips and 2 crushed fifth avenue blend in well and pour into the cake pan then do the second cake mix the same way the left over batter can be used for cup cakes.. You will have some left for each layer don't try to use all the batter in one pan. Bake at 350 til done about 35 to 40 min test with tooth pick. Be sure to line the cake pans with wax paper this cake will stick with the chips and candy.
filling: mix all the ingredients together and mix if too stiff and a little water one teaspoon at a time so not to get too runny
Icing: mix all ingredients together and blend til the it is smooth for icing the cake but not to wet. You can add a little water it too stiff but be very careful not to add to much at a time.
When cakes are done and on cooling racks slice to have 4 layers let cool all the way through before assembling the cake. Lay one layer down spread thick layer of filling then layer of chocolate icing and keep doing till you top off. Then ice the whole cake with the chocolate frosting.