"What have you done recently?" is correct, but this question is very specific. In most cases, you would not say this. The question demands a specific answer. To answer it, the friend must say something specific, like "I finished the Spanish course I was taking."
If you want to adopt a friendlier tone that leaves the option of a nonspecific or rambling response, then say
"What have you been doing?"
or, as Paul suggested,
"What have you been up to?"
The reason that "doing" sounds so much friendlier and open than "done" is that present participles are imprecise. They create images open to interpretation. Present participles can mean almost anything the speaker wants them to mean, so long as that meaning remain connected to the underlying verb.