  Narrow dark resonances associated with electromagnetically induced
transparency play a key role in enhancing photon-photon interactions. The
schemes realized to date relied on the existence of long-lived atomic states
with strong van der Waals interactions. Here, we show that by placing an
atomically thin semiconductor with ultra-fast radiative decay rate inside a
\textcolor{black}{0D} cavity, it is possible to obtain narrow dark or bright
resonances in transmission whose width could be much smaller than that of the
cavity and bare exciton decay rates. While breaking of translational invariance
places a limit on the width of the dark resonance width, it is possible to
obtain a narrow bright resonance that is resilient against disorder by tuning
the cavity away from the excitonic transition. Resonant excitation of this
bright resonance yields strong photon antibunching even in the limit where the
interaction strength is arbitrarily smaller than the non-Markovian disorder
broadening and the radiative decay rate of the bare exciton. Our findings
suggest that atomically thin semiconductors could pave the way for realization
of strongly interacting photonic systems in the solid-state.
