  We study top-assisted di-Higgs production via $cg \to tH \to thh$, where $h$
is the 125 GeV scalar boson, and $H$ is the $CP$-even heavy Higgs. The context
is the two Higgs doublet model without a $Z_2$ symmetry, where the extra Yukawa
coupling $\rho_{tc}$ generates $tH$ production, with the extra top Yukawa
$\rho_{tt} \simeq 0$ to avoid $gg \to H$ constraints. We find that discovery is
possible for $m_H$ around 300 GeV or so at the LHC, but would need finite
$h$-$H$ mixing angle $\cos\gamma$ to allow for finite $\lambda_{Hhh}$ coupling,
and $\rho_{tc}$ also needs to be not too small. A sizable $\rho_{tc}$ could
drive electroweak baryogenesis, which further motivates the search.
