Mix cooking chocolate (or you may use chocolate melts) with heavy cream.
Cook in a microwave for 1 minute.Alternatively you may use a double boiler or steamer to melt the chocolate on slow heat on gas stove
Stir and cook for 1 minute or you can just pour hot cream on chocolate
Mix well with spatula and do not use whisk that may add bubbles.
Cover with a cling wrap and ensure it touches top of chocolate mix.
This ensures that there is no dry crust on top.
Let this sit for at least 12 hours at room temperature @ around 20-25 degrees C.
If it is too hot and then refrigerate 30 minutes to get a spreadable consistency.
If ganache is not spreadable,you may heat in microwave for 15 seconds.
Mix with a spatula and spread on cake.
This may be bit shiny(especially if heated in microwave) at start.
However, you get nice consistency when it sets after 10 minutes.
Place second layer of cake on top.
Spread chocolate ganache evenly.
Garnish with berries and refrigerate 1 hour before you serve.
Serve it with ice cream and hot chocolate sauce as per your choice.