The existence of extra Higgses in Nature could lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe. We discuss two possible such scenarios, analyzing the LHC `smoking gun' signatures of such a phase transition: We first consider a two-Higgs-doublet model, and show that the observation of the decay A0  → H0 Z at the 14 TeV run of LHC in llbb or bbWW final states would signal a strong EW phase transition as required by baryogenesis. We then discuss Higgs portal scenarios, where resonant di-Higgs production may constitute a powerful probe of the nature of the phase transition.