Mosaic cake ( Mozaik pasta )

When I was in Turkey I made this cake years and years after I came to USA I forgot to make it. I was visiting my Turkish friend today she served with tea and I remember how much I loved it. I had to make it again. I found couple of recipes from online but I made some changes. here it is,
Ingredients

8 oz milk
1.5 tbsp butter
5 tbsp cocoa
(2 pieces baking chocolate melted )
optional
1 orange zest
6 tbsp sugar
1 tbsp vanilla
2 packages Turkish Ulker tea  biscuits
(available at Turkish groceries)
1/2 cup walnut

Preparation Method 
Mix all the ingredients except biscuits and walnuts in a large plastic bowl with a spoon. Break the biscuits small pieces. Put them into mixture with walnut and mix together. Place the mixture in the center a long piece of aluminum foil. Give it a long log-like shape with the spoon.  Then with the aluminum foil, first fold over the long sides tightly, then fold the rims. Put it in a freezer. When you want to serve take out from freezer and slice it.