White Chocolate Mousse Tarts

On a lightly floured surface, roll out dough 1/8 inch thick. Line twenty-four 3 3/4-by-1 3/4-inch rectangular tart pans, rerolling scraps as needed. Pierce bottoms of shells all over with a fork. Transfer pans to a parchment-lined rimmed baking sheet; refrigerate or freeze until firm, about 30 minutes.

Meanwhile, preheat oven to 350°F. Bake shells until dry, 15 to 18 minutes. Let cool completely on a wire rack.

In a small bowl, sprinkle gelatin over the ice water. Let soften about 5 minutes. Meanwhile, in a small saucepan, bring 1/2 cup cream to a boil. Remove from heat. Add softened gelatin, stirring for 30 seconds to dissolve completely.