In a separate bowl (larger than the first one I have pictured) measure 1/2 cup cold water. Sprinkle 2 envelopes unflavored gelatin on top. Let the gelatin "bloom" or thicken for a few minutes, and add 1 1/2 (one and a half) cups boiling water and dissolve.
Add the can of condensed milk. Stir and allow to cool to room temperature.