The raster-scanned irradiation of ultrathin sub-micrometer crystalline gold colloidal prisms with the tightly focused spot of a femtosecond, near-infrared laser triggers the deterministic deformation and partial melting of nanometer-sized areas of the nanoprisms. The morphological modification of the Au nanoprisms evidences extremely localized sources of heat, the in-plane distribution of which varies with the particle shape and laser polarization. We demonstrate for the first time the direct relationship between heat source density and surface plasmon local density of states (SP-LDOS), which describes quantitatively the rich modal structure of the surface plasmons sustained by the 2D metallic platelets, independently of the knowledge of the illumination configuration. Green’s Dyadic numerical simulations confirm that the optical excitation of the 2D SP modes results in the subwavelength hot imprinting of the SP modal pattern onto the metal surface.