Three-milk gelatin combines the beloved tres leches flavor in a jiggly, cool dessert. This family-friendly treat is a refreshing, creamy twist on Mexico's most famous cake.
Add 0.5 cup cold water to a medium bowl and sprinkle the gelatin evenly on top. Let it bloom for 5 minutes until it thickens.
Heat 1 cup whole milk in a saucepan over medium-low until steaming, not boiling. Stir in the bloomed gelatin until fully dissolved, about 1-2 minutes.
Add sweetened condensed milk, evaporated milk, granulated sugar, and vanilla extract to the pan. Whisk well until smooth and sugar dissolves, keeping heat low to prevent scalding.
Remove from heat and let the mixture cool until just warm to the touch (not hot), about 10 minutes, stirring occasionally to prevent a skin forming.
Pour the mixture into a lightly greased 6-cup gelatin mold or bundt pan. Chill uncovered for 30 minutes, then cover and chill 4+ hours until fully set. Unmold by running a thin knife around the edge and inverting onto a plate.