Mango Margarita Pie with Gingersnap Crust

1 1/4 cups gingersnap cookie crumbs (about 20 cookies)
5 tablespoons unsalted butter, room temperature
3 tablespoons plus 1 cup granulated sugar (divided)
2 envelopes unflavored gelatine
1/2 cup fresh lime juice
4 eggs, separated
1 cup pureed ripe mango (1 medium mango)
1/4 cup tequila (see note)
3 tablespoons orange-flavored liqueur
1 cup whipping cream
Paper-thin mango and lime slices for garnish

Heat oven to 350 degrees F.

Prepare crust by combining cookie crumbs, butter and 3 tablespoons sugar in 9 1/2-inch pie plate. Mix well with hands and press mixture up sides of pan. Bake in preheated oven until lightly browned, 8 to 10 minutes, and set aside on rack to cool.

Prepare filling by stirring gelatin, lime juice and egg yolks together in small saucepan and let stand a few minutes to soften gelatin. Cook over low heat, stirring constantly with wooden spoon, about 5 minutes, until gelatin melts and mixture thickens slightly. Don't let it boil.

Stir gelatin mixture, mango, tequila and liqueur together in large bowl. Refrigerate about 1 hour, stirring often, until it has the consistency of unbeaten egg whites. (If it thickens too much, set over bowl of hot water and whisk to thin it.)

Meanwhile, put egg whites in non-aluminum saucepan over low heat - or in double boiler over rapidly boiling water - and beat at low speed with hand-held electric mixer or whisk until foamy. Turn speed to high and gradually add remaining 1 cup sugar, beating until mixture holds stiff peaks, 6 to 8 minutes, with electric mixer. Set aside to cool.

In another bowl, beat cream until stiff. Fold cream and cooled egg white mixture into mango mixture. Pour into prepared piecrust, mounding it at center.

Refrigerate pie until set, about 1 hour. Just before serving, overlap mango slices around edge of pie and arrange lime slices in decorative pattern in center.

NOTE: Orange juice may be substituted for the tequila and orange liqueur.