It's unclear what "ENC Data" means to you. An ENC is a program that you provide. When run it emits data (classes, parameter values, and global variable values), but that data must be in YAML format already, so I suppose it's not what you're looking for. Perhaps your particular ENC relies on an external data file, and it's that data you want to pass on to clients; in that case, we'll need some more information about the nature of that file before we can give you any detailed help.
Generally speaking, however, formatting raw external data within Puppet probably depends either on writing a custom function or on use of OS utilities or an external program via the built-in generate() function.
John