  We now have mounting evidences that the circumgalactic medium (CGM) of
galaxies is polluted with metals processed through stars. The fate of these
metals is however still an open question and several findings indicate that
they remain poorly mixed. A powerful tool to study the low-density gas of the
CGM is offered by absorption lines in quasar spectra, although the information
retrieved is limited to 1D along the sightline. We report the serendipitous
discovery of two close-by bright z_gal=1.148 extended galaxies with a
fortuitous intervening z_abs=1.067 foreground absorber. MUSE IFU observations
spatially probes kpc-scales in absorption in the plane of the sky over a total
area spanning ~30 kpc^-2. We identify two OII emitters at z_abs down to 21 kpc
with SFR~2 M_sun/yr. We measure small fractional variations (<30%) in the
equivalent widths of FeII and MgII cold gas absorbers on coherence scales of
8kpc but stronger variation on larger scales (25kpc). We compute the
corresponding cloud gas mass <2x10^9M_sun. Our results indicate a good
efficiency of the metal mixing on kpc-scales in the CGM of a typical z~1
galaxy. This study show-cases new prospects for mapping the distribution and
sizes of metal clouds observed in absorption against extended background
sources with 3D spectroscopy.
