Ganache is not much more than melted chocolate with cream in it to keep it flowy. If you melt chocolate and pour it out, it will harden again—great for making chocolate bark or creating a hard coating around fruit. Not really what you want for icing, for instance. How much cream (fat) you want to add depends on how you want the ganache to act but basically, the more cream, the less the chocolate will set. If you do a 2:1 chocolate:cream ratio, you can make a soft icing for cakes or cookies. Oh and for shine, you add butter. Gets better and better, doesn’t it?
Shiny Chocolate Ganache
250 g heavy cream (about 1c)
500 g dark chocolate, chopped fairly evenly
1 tbs unsalted butter, softened
Heat the cream to just simmering in a small saucepan. Immediately pour over the chocolate in a heat-proof bowl and stir after 1 minute. Add butter and stir through. Use an off-set spatula to spread ganache over cookies (might I recommend peanut butter cookies?) or tarts.