Step 1: Prepare the Mangoes. Peel your ripe mangoes and cut the flesh away from the pit. Reserve about half a cup of small diced mango pieces for garnish later. Place the remaining mango flesh into a blender or food processor and blend until you achieve a super smooth, lump-free puree. Set aside.
Step 2: Bloom the Gelatin. In a small heatproof bowl, sprinkle the gelatin powder over 1/2 cup of cold water. Let it sit for 5-10 minutes until the gelatin absorbs the water and swells, becoming spongy.
Step 3: Dissolve the Gelatin. Bring about 1 cup of water to a simmer in a small saucepan. Once simmering, remove from heat and add the bloomed gelatin mixture to the hot water. Stir continuously until the gelatin is completely dissolved and the liquid is clear. If needed, gently heat over low heat, but do not boil.
Step 4: Combine Ingredients. In a large bowl, whisk together the warm dissolved gelatin mixture, granulated sugar, and evaporated milk until the sugar is fully dissolved.
Step 5: Add Mango Puree. Gently fold the mango puree into the gelatin-milk mixture. Stir until everything is well combined and the mixture is uniform in color.
Step 6: Chill the Pudding. Pour the mixture into individual serving molds, ramekins, or a large serving bowl. Cover each mold with plastic wrap to prevent a skin from forming.
Step 7: Set and Serve. Refrigerate for at least 4-6 hours, or preferably overnight, until completely set and firm. Before serving, you can briefly dip the bottom of the molds in warm water to help release the pudding, then invert onto serving plates. Garnish with the reserved fresh diced mango pieces.