Exploring the mechanism that explains the origin of the masses of elementary particles, fermions and gauge bosons, remains one of the main objectives of the Particle Physics program of the LHC. One experimental probe consists of measuring the strength of the interaction between the Higgs boson and the Top quark, named top-Yukawa coupling, using the full dataset collected by the ATLAS experiment during the Run 2 operational period of the proton-proton collider LHC. Exhaustive studies of those processes that involve the associated production of Higgs bosons and Top quarks carry out in the ATLAS collaboration are reviewed. In particular, the associated Higgs production with a single top quark has the potential to measure the size and the sign of the top-Yukawa coupling. The exploration of this process is challenging due to the small rate predicted by the current theory of the Standard Model. Therefore, sophisticated analysis techniques that integrate Machine Learning developments are needed. Such rare process cannot be observed even with the full LHC Run-2 statistics and indeed an observation of this signal would be a clear indication of new physics beyond the Standard Model, as it would imply deviations from the expected value of both the sign and magnitude of the top-Yukawa coupling.