Everybody loves chocolate sauce. But while the lusciousness of a pourable ganache is hard to beat, the cream base means it can fall a little on the rich side. For a sauce that can be poured at will, and isn't so cloying, a sugar-syrup base is the way to go.
Keep in mind that the choice of chocolate will define the result; a bittersweet chocolate, around 70% cocoa solids, will balance the sweetness of the sugar syrup and keep the chocolate flavour front and centre. We recommend any couverture you'd be happy to eat as a block, but play around and find the chocolate you like. A little cocoa powder will also add a bit more body and a deep, rich colour. The rest is simple: heat, stir and pour over everything. Churros, of course, are a great place to start.