Using confocal microscopy and small-deformation rheology, we demonstrate the formation of stable thermoreversible gelatin-based gels with colloidal fractal-type microstructure. The opaque particle gels were made by cooling of transparent mixed aqueous solutions of gelatin (1-3 wt %) and starch (7 wt %) from 40 to 24 degrees C. The mechanism involves starch-induced gelatin self-association into phase-separated gelatin-rich microgel particles, followed by diffusion-limited cluster aggregation into a particle gel network.