How to make
Crush the tea biscuits in a suitably large bowl, but not too finely. Toast the walnuts briefly in a dry pan, being careful not to burn them, then cut them with a knife into smaller pieces if needed and pour them over the biscuits.
For the chocolate syrup, mix the sugar and cocoa, mix with a wire whisk and gradually add the water, without stopping the stirring. Add the butter and bring the mixture to a boiling point on the stove, by stirring occasionally.
Once it boils, stir for a few minutes until it thickens slightly and remove from the heat.
Allow the mixture to cool for about 10 minutes, pour it over the biscuits and stir until the mixture is homogenized.
Line a cake tin with a detachable ring with baking paper on the bottom, pour the mixture and level it out by pressing it down nicely. Put it in the fridge while you make the chocolate ganache.
For it, heat the cream well and pour in the crushed chocolate/couverture. Wait for 3 seconds and mix until smooth.
If the mixture seems too thick, add a little milk, if it is thin - pour both. I also added cocoa and a little more milk.
Pour the ganache over the biscuit cake and place it back into the refrigerator. After about 15-30 minutes, your Wonderful Chocolate Biscuit Cake is ready to eat.
Enjoy!