When you want to melt chocolate bars have to use the bain-marie way.
Put a pot on the fire full of water and inside it put another pot smoller than the first.
In this way chocolate doesn’t directly in touch with fire and doesn’t risk to burn!
During all the melting you have to turn chocolate so to fast the procedures.
When it’s totaly melted, continue to twist it and drain it into mold, or mix of ingredients, or in ice-cream at the end of iceing.