Preheat the oven to 356º F (180°C). Line a round cake pan of about 9.80 inches (25 cm) in diameter with parchment paper.
Place the cookies and nuts in a food processor and grind for a few seconds until they are in small pieces but not completely powdered. They can also be cut with a knife on a cutting board.
Place the egg whites with the salt and cream of tartar in a clean, dry bowl. Beat them with an electric mixer for 3-4 minutes until they are nougat-like (when they begin to rise sharply, are white and somewhat firm).
While continuing to beat, gradually add in the sugar with the baking powder and continue beating for another 3 minutes until a glossy meringue with stiff peaks is obtained.
Add the vanilla extract, cookies and ground nuts and incorporate with a rubber spatula in a folding way. Do not use the mixer anymore so that the whipped egg whites do not droop.
Pour the mixture into the pan and bake at 356º F (180° C) for about 30-40 minutes until the mostachon begins to brown slightly on top. Remove from the oven, carefully turn out and let it cool down completely.
For the cream and to finish:
In a bowl add the whipping cream and beat with an electric mixer for 2-3 minutes until soft peaks form.
In another bowl, beat, using the same mixer or a hand whisk, the cream cheese with the cream, powdered sugar, vanilla and salt for 2 minutes until the mixture is light and fluffy.
Add in the whipped cream in three separate additions to the cream cheese mixture using a rubber spatula. Mix by doing folding motions. Refrigerate this mixture until needed.
Place the meringue base on a large plate that will be where the mostachon will be served.
Add the cream on top and spread with a spatula over the entire mostachon base. Then add the mango cut into small cubes and refrigerate the mostachon for 30 minutes before cutting it.