Step 1: Prepare the Mangoes. Peel and dice the mangoes. Reserve about 1 cup of finely diced mangoes for garnish. Puree the remaining mangoes in a blender or food processor until perfectly smooth. You should have approximately 3 cups of mango puree.
Step 2: Bloom the Gelatin. In a small bowl, sprinkle the gelatin powder over 1 cup of cold water. Let it sit for 5-10 minutes until it swells and becomes spongy. If using leaf gelatin, soak sheets in cold water until soft, then squeeze out excess water.
Step 3: Dissolve Gelatin. Bring 1 cup of water to a boil. Pour the boiling water over the bloomed gelatin (or add squeezed leaf gelatin to hot water) and stir constantly until the gelatin is completely dissolved. Ensure there are no lumps or undissolved granules. Set aside to cool slightly.
Step 4: Prepare Sweetened Milk Mixture. In a separate bowl, combine the granulated sugar with 1/4 cup of hot water. Stir until the sugar is fully dissolved. Add the evaporated milk to this sugar mixture and stir well to combine.
Step 5: Combine Ingredients. In a large mixing bowl, pour in the mango puree. Slowly add the dissolved gelatin mixture, stirring constantly to ensure it is evenly incorporated. Then, gradually stir in the sweetened evaporated milk mixture. Mix until everything is thoroughly combined and smooth. Taste and adjust sweetness if desired.
Step 6: Strain (Optional but Recommended). For an extra silky smooth texture, pass the entire mixture through a fine-mesh sieve into a clean bowl or pouring jug. This removes any tiny mango fibers or undissolved gelatin bits.
Step 7: Set the Pudding. Pour the mixture into individual serving molds, ramekins, or a large serving bowl. Cover with plastic wrap and refrigerate for at least 4-6 hours, or preferably overnight, until the pudding is fully set and firm. When ready to serve, unmold by briefly dipping the bottom of the mold in warm water and inverting onto a plate. Garnish with the reserved fresh diced mangoes.