Transmission spectroscopy of exoplanet atmospheres routinely reveals light chemical species, such as H2O, Na, and K. Heavier molecules, such as titanium oxide and vanadiam oxide, have long been predicted to be present in the hottest exoplanet atmospheres, but definitive detections of these species have proven elusive. Ground-based optical transmission spectroscopy offers a solution to this dilemma. We will present the complete optical transmission spectrum of the hot Jupiter WASP-19b, obtained with the VLT FORS2 spectograph, which reveals the presence of TiO at >7-sigma confidence. The results from an extensive atmospheric retrieval analysis, indicating the presence of H2O, Na, and a strongly scattering haze, will be presented. Finally, we will examine the prospect of ground-based transmission spectroscopy as an avenue to constrain heavy metal chemistry in exoplanet atmospheres.