I have found several candy bar cakes, but none called Fifth Ave. I'll post a couple of them here.

Milky Way Bar Cake

6 Milky Way bars
1 c butter, divided
2 c sugar
4 eggs
1/2 tsp baking soda
2 1/2 c sifted flour
1 1/4 c buttermilk
1 tsp vanilla
1 c chopped nuts

melt candy bars and 1/2 c of butter in saucepan over low heat. beat remaining 1/2 c butter and sugar in bowl till fluffy. add eggs one at a time and beat well. add sifted flour and soda alternately with buttermilk, sstirring until smooth. add melted candy. stir in vanilla and nuts. pour into greased and floured 10 inch tube pan and bake 1 hour 20 min at 350. top will be dark.


CANDY BAR CAKE

1 stick butter
1/2 c crisco
1 c water
1/4 c cocoa
1/2 tsp salt
1 tsp baking soda
2 c flour
2 c sugar
2 eggs
1/2 c buttermilk
1 tsp vanilla

in small pan mix butter, crisco, water, cocoa, and salt. bring to boil. in large bowl put flour and sugar. pour hot liquid over mixture and mix well. add eggs, buttermilk, soda and vanilla. pour into a greased 17x13x3/4 pan. bake 400 for 25min.

icing
1 stick butter
1/4 c cocoa
1/3 c buttermilk
1/2 c coconut - opt
1 lb powdered sugar
1 tsp vanilla
1/2 c chopped nuts

in pan place butter, cocoa, buttermilk, and bring to boil. add powdered sugar, vanilla, nuts and coconut. ice cake while hot.

ALMOND JOY CAKE

1 box chocolate butter cake mix
24 large marshmallows
1 c milk
1 large can coconut

bake cake mix according to directions on box. let cake cool. heat milk, add coconut and marshmallows and set aside.

frosting
2 c sugar
2 c semisweet chocolate
1/4 c white karo syrup
1 stick butter
1/2 c milk

melt and boil 1 min and beat til creamy. punch holes in cake. pour marshmallow mix over cake, then add frosting


TURTLE CAKE

1 box german choclate cake mix
1 14oz bag caramels
3/4 c butter
1/2 c evaporated milk
1 c chopped pecans
1 c chocolate chips

in saucepan, over low heat, melt caramels with butter and evaporated milk. mix cake according to directions on box. pour half of batter into greased and floured 13x9 pan. bake 350 for 15 min. remove from oven and top with caramel mixture, then chocolate chips and pecans. pour second half of cake batter over top. bake 20 min. at 350. may frost if desired. may be prepared a couple of days in advance.

hope those help.