In theory, you don't really need two steps, you could use a MIDI instrument to play the notes into a package. But timings will usually be way off, and the printed music will not be accurate.

How about learning abc notation? That is really quick and easy for melodies, and there are plenty of programs, including mine, which can translate abc to sheet music.

Alternatively, my own program also has a drag and drop facility where you can drop notes onto the score, and then immediately play it back if you need to check what you have done. The score can then be printed out.

Download HARMONY from my site