Grease a 16×12 inch baking sheet. Then line it with parchment paper and brush lightly with melted butter on top of the paper.
In a bowl over a pot of simmering water over medium heat, place the egg yolks, mango puree, condensed milk, and vanilla and cook while continuously whisking until thick, making sure not to let the egg scramble. (If it smells eggy or like scrambled eggs, it is overcooked) Let cool and mix in the finely chopped mango pieces.
In a cold bowl, whisk the chilled cream until stiff peaks. Fold in the mango filling 1/3 at a time until everything is fully incorporated, taking care not to deflate the cream. Set aside and keep chilled.
Whisk the egg whites with the cream of tartar until the soft peak stage. Carefully sprinkle a light layer of sugar onto the egg whites, whisking well after each addition. Whisk until stiff but not dry. Spread meringue onto the prepared baking sheet, smoothening the top.
Bake in an oven preheated to 175 degrees Celsius for 30 minutes or until set and golden in color.
Immediately after baking turn the meringue out onto a clean countertop dusted with powdered sugar and roll to set the shape. Hold this shape for 5 minutes.
Unroll, spread the mango filling onto the meringue, leaving 2 inches free on one edge, and roll up tightly. Dust with more powdered sugar and chill before serving.
Serving Size 4-6 servings