The progenitor systems of cataclysmic variables, gravitational wave mergers and type Ia supernovae are believed to arise from a mass transfer process known as common envelope (CE) evolution. Despite its importance, CE evolution remains one of the largest unresolved issues in stellar astrophysics, mainly due to the lack of observational benchmarks that connect post-CE parameters with their pre-CE initial conditions. Similar to the initial-final mass relation for single white dwarfs in star clusters, identifying post-CE systems in star clusters can circumvent this issue by providing an independent constraint on the system's age. However, until recently, only two white dwarf-main sequence post-CE systems were ever associated with a star cluster. For the first time, we conducted a systematic search for white dwarf and main-sequence binary systems in 299 Milky Way open star clusters. Coupling Gaia DR3 photometry and kinematics with multiband photometry from Pan-STARRS1 and the Two Micron All Sky Survey, we apply a supervised machine learning-based approach and find 52 high-probability candidates in 38 open clusters. For a subset of our systems, we present follow-up spectroscopy from the Gemini and Lick Observatories and archival light curves from the Transiting Exoplanet Survey Satellite, Kepler/K2, and the Zwicky Transient Facility. Examples of M dwarfs with hot companions are spectroscopically observed, along with regular system variability. While the kinematics of our candidates are consistent with their host clusters, some systems have spatial positions offset relative to their hosts, potentially indicative of natal kicks. These efforts are the first steps of a larger effort to produce an observational benchmark catalog of post-CE binaries in clusters which will ultimately provide fundamental observational constraints on one of the most uncertain yet crucial phases of binary evolution.