Upon assuming the $B-L$ Supersymmetric Standard Model (BLSSM) as theoretical framework accommodating a multi-Higgs sector, we assess the scope of the High Luminosity Large Hadron Collider (HL-LHC) in accessing charged Higgs bosons ($H^pm$) produced in pairs from $Z$ decays. We show that, by pursuing both di-jet and tau-neutrino decays, several signals can be established for $H^pm$ masses ranging from about $M_{W}$ to above $m_t$ and $Z$ masses between 2.5 TeV and 3.5 TeV. The discovery can be attained, even in a background free environment in some cases, owing to the fact that the very massive resonating $Z$ ejects the charged Higgs bosons at very high transverse momentum, a kinematic region where any SM noise is hugely depleted.