  In 2002, V838 Monocerotis (V838 Mon) erupted in a red novae event which has
been interpreted to be a stellar merger. Soon after reaching peak luminosity,
it began to cool, and its spectrum evolved to later spectral types. Dust was
also formed in the post-merger remnant, making it bright in the mid-infrared.
Interferometric studies at these wavelengths have suggested the presence of a
flattened, elongated structure. We investigate, for the first time, the
structure and orientation of the dusty envelope surrounding V838 Mon in the
$L$(2.8-4.2 $\mu$m) band using recent observations with the MATISSE instrument
at the VLTI. We perform simple geometrical modelling of the interferometric
observables using basic models (disks, Gaussians, point sources, along with
their combinations). We also reconstructed an image and analyzed the
corresponding $L$-band spectrum. This study indicates the presence of an
elongated, disk-like structure near 3.5$\mu$m, similar to what has been
observed in other wavelength regimes. In particular, the orientation at a
position angle of -40 degrees agrees with prior measurements in other bands.
The dusty elongated structure surrounding V838 Mon appears to be a stable and
long lived feature that has been present in the system for over a decade. Its
substructure and origin remain unclear, but may be related to mass loss
phenomena that took place in the orbital plane of the merged binary.
