Ab Augmented Major 7th, 1st inversion (B# in the bass)
Also written as Abaug(maj7)/B#.
Notes, from the bass up
B# (bass)EGG#
The same notes as Ab Augmented Major 7th (B#, E, G and G#), rearranged so B# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.