The preparation of wide-gap CsPbCl3 thin films from solution is impeded by the poor concomitant solubility of the precursor salts PbCl2 and CsCl. In the present study, we prepared superlattices of PbCl2 and CsCl by thermal evaporation. The superlattice shows an intense photoluminescence at 413 nm with a narrow line width of 10 nm (FWHM), which agrees with reports of CsPbCl3 single crystals. Most notably, the resulting layer structures support amplified spontaneous emission (ASE) in the deep blue spectral region at 427 nm (width 2.2 nm) under pulsed optical excitation (355 nm, 300 ps) above a threshold energy density of 190 μJ/cm2 at room temperature (RT). This is the first report of CsPbCl3 thin films showing ASE at RT.