B over C (major triad over major triad a half step apart). This can also be C triad over B triad.
C           E        G           B           D♯       F♯
1           3        5           7           ♯9       ♯11

Parent scales is E harmonic minor (no 4).
E     F♯ G           B  C        D♯ 
1     2  ♭3          5  ♭6       7

Related chords.
| Am7 | B7♭9 | Cmaj7♯11 | D7 | E♭13 | Em7 | F♯m7♭5 |