Tokøta from Mastering.com shows how to draw MIDI chords directly into the piano roll instead of playing them, then use Logic Pro's Q-flam quantize option to add a staggered, human feel.
After voicing a triad by moving the middle note up an octave for better voice leading, the notes are quantized to 16th notes, then flammed so the chord sounds like it's being rolled by hand rather than struck all at once.
Velocity, note length, and a touch of delay get adjusted so the chord sits naturally in the groove instead of cutting off abruptly.
A second bass layer is added an octave below using a deep square patch, filling out the low end alongside the existing drums and chords.