FamousCharlie Brown Christmas chordA Charlie Brown Christmas, 1965 · Vince Guaraldi (music), Lee Mendelson (lyrics); Vince Guaraldi Trio
F major triad over an E♭7 shell (E♭, G, D♭)
The second chord of the opening vamp, alternating with F major seventh (Fmaj7 to E♭7♯11)
An E♭ dominant seventh with an F major triad floating on top, which adds the ninth (F), the sharp eleventh (A) and the thirteenth (C). In 'Christmas Time Is Here' from A Charlie Brown Christmas it swaps back and forth with F major seventh in the opening vamp, a whole step below the home chord. The A natural against the E♭ root gives it its soft, wintry jazz glow.
Also called Charlie Brown, Charlie Brown chord, the Guaraldi ♭VII7♯11
Sources: Josh Walsh, 'The Vince Guaraldi Charlie Brown Christmas chord', Jazz Library · Hooktheory TheoryTab, 'Christmas Time Is Here' · LadyDpiano, 'How To Play: Christmas Time Is Here' (2012) · PianoGroove, 'Christmas Time Is Here - Deep Dive'