Peel, pit, and dice the mangoes, then puree the chunks in a blender until smooth.

Mix the gelatin or agar agar with cold water in a bowl and let it sit for 30 to 45 seconds to bloom.

In a mixing bowl, whisk together the mango puree, coconut milk, and sugar until combined.

Heat the mango mixture in a small pot over medium-low heat for about 4 to 5 minutes, whisking continuously.

Pour the mixture into serving bowls or molds, cover, and refrigerate for at least 6 hours to set.