Hydrate gelatin in water.
Prepare crème anglaise: cook cream, yolks, and sugar to 82°C, stirring constantly.
Remove from heat, weigh 140 g, and melt in the hydrated gelatin.
Add mango purée and emulsify with an immersion blender.
When cooled to 35°C, add cold cubed butter and blend again.
Pour 230 g into a 16 cm silicone mold (or a ring lined with acetate and plastic wrap).
Refrigerate for 3 hours, then freeze.