Ganache

If you were to ask me what my favourite icing is, I'd have to say it depends. That's a tricksy little phrase that we learnt in med-school. It bought you some breathing space before you committed to an answer. (Of course the inquisitor wouldn't stop there, and would continue to grill you until every last drop of knowledge you possessed on the subject was wrung out of you!) 

So, what does it depend on? What it's going to be used for: 
My favourite icing to eat is chocolate cream cheese icing. 
My favourite icing to pipe is Swiss meringue buttercream.  
My favourite icing to use for covering a cake before applying fondant is ganache. (Which tastes heavenly, too - it's definitely a strong contender as the answer to question no. 1). 

I love to use ganache on cakes because it glides on so easily and smoothly, and sets hard - creating the perfect surface for applying fondant. 

simply ganache...

To make ganache you need chocolate and cream. And it must be "heavy cream" / whipping cream - which has a 35-40% fat content.
You vary the ratio between the chocolate and cream, depending on the intended use of the ganache and also depending on what chocolate you're using. 

For covering cakes:
-with dark chocolate use a ratio of 2:1 chocolate to cream - gram for gram/ ml's 
-with milk chocolate use 2.5:1 
-with white chocolate use 3:1 

(Not everyone uses these ratios, but they're the ones I've had success with.) 

Dark Chocolate Ganache

500g dark chocolate, cut into small, even sized pieces.
250ml cream (it must be whipping cream - 35-40% fat) 

Place both ingredients into a double boiler (a heatproof bowl placed over a pot of simmering water) OR in a microwave-proof bowl.
Heat slowly, stirring frequently until all the chocolate has melted. 

OR bring the just the cream to boil, then pour over the chocolate. Leave undisturbed for a few minutes, then stir until smooth.

Leave to cool down at room temperature. Place some cling-wrap onto the surface of the ganache to prevent a crust forming. 
Spread onto your cake once the ganache has reached a peanut butter consistency. 
If it sets firmer, microwave it for a few seconds to soften it again. 

If you want to calculate the amount of ganache you need to cover a cake, Jane from "I Want Sprinkles"in Australia has created the Ganacherator to help out:
https://www.facebook.com/theganacherator

Isn't that neat?!

Happy ganaching!

xxM