Ingredients

Crust

Preheat oven to 325 F

In a 9 1/2-inch springform pan blend all crust ingredients with your fingertips until combined well and press evenly onto bottom and 1 inch up side of pan. Bake crust in middle of oven 10 minutes and transfer to a rack to cool.

Mousse

In a heavy saucepan whisk together sugar, cornstarch, and salt and gradually whisk in milk, whisking until mixture is smooth. Sprinkle gelatin over milk mixture and let stand 1 minute to soften gelatin.

In a small bowl whisk together yolks. Bring milk mixture to a boil over moderate heat, whisking constantly, and remove pan from heat. Gradually whisk about 1 cup milk mixture into yolks and whisk yolk mixture into remaining milk mixture. Simmer custard, whisking, 3 minutes (custard will be thick but pourable) and remove pan from heat. Whisk in butter, zest, and lime juice until combined and let custard stand 10 minutes to allow flavors to blend.

Pour custard through a fine sieve into a metal bowl, pressing custard with a rubber spatula if necessary, and set in a larger bowl of ice and cold water. Cool custard, stirring occasionally with a rubber spatula until thick but not completely set (custard should mound slightly when dropped from a spoon), about 20 minutes.

In a bowl with an electric mixture beat cream until it holds soft peaks. With a alarge rubber spatula gently fold whipped cream into custard and gently spoon mousse into crust. Chill tart, uncovered, until set about 4 hours.

Note: Tart keeps, covered and chilled, 3 days.