Let's start with what you want to do with your ganache:

For a thick ganache, used for filling macarons, for instance:

use 3/4 chocolate and 1/4 heavy cream

For a medium ganache, used for frosting:

use 1/2 chocolate and 1/2 heavy cream

For a smoother ganache, used for icing:

use 1/4 chocolate or 1/3 and 3/4 heavy cream or 2/3

Got it? Let's plod on. In a double boiler – using a bowl over a pan of simmering water – melt the chocolate with the cream and that's it!

Let cool before you use it for filling.

Cool it just a few minutes to frost a cake and hide its imperfections. You will then use the smoother ganache to frost your cake.

To make a perfectly glazed chocolate cake, sit it on a wire rack with a plate or baking sheet underneath. First frost to remove all the imperfections with a large knife or spatula. Then with the saucepan of still warm and liquid smoother ganache, run the ganache over the cake for a perfect sheen.