Instructions

for the browned-butter tart shells

Adjust oven rack to middle position and heat oven to 350 degrees. Spray two 4-inch tart pans with removable bottoms with vegetable oil spray; set aside. Whisk ½ cup (2½ ounces) all-purpose flour, 1 tablespoon plus 2 teaspoons sugar, and pinch salt together in medium bowl. Melt 4 tablespoons unsalted butter in small saucepan over medium-high heat, swirling saucepan occasionally, until foaming subsides. Cook, stirring and scraping bottom of saucepan with spatula, until milk solids are dark golden brown and butter has nutty aroma, 1 to 3 minutes. Remove sauce pan from heat and carefully add 1 tablespoon water (mixture will sputter and steam). When bubbling subsides, add butter to bowl with flour mixture and stir until well combined. Let dough rest until just warm to the touch, about 5 minutes.
Divide dough in half, then transfer each half to prepared tart pans. Use your hands to evenly press and smooth dough over bottom and up side of pan (using two-thirds of dough for each bottom crust and remaining third for sides). Place pans on wire rack set in rimmed baking sheet and bake until crusts are golden brown, 23 to 28 minutes, rotating sheet halfway through baking. Let cool completely, about 30 minutes.

for the curd

During last 10 minutes of cooling, whisk ¼ cup passion fruit puree, 3 tablespoons sugar, and 1 tablespoon cornstarch together in small saucepan. Cook over medium-low heat, stirring constantly, until thick paste forms, 2 to 4 minutes. Off heat, add 1½ ounces chopped white chocolate and whisk until melted, then whisk in 3 tablespoons unsalted butter cut into ½-inch pieces in 2 additions until mixture is smooth and glossy. Divide curd evenly between cooled tart shells and smooth tops with small offset spatula. Refrigerate, uncovered, until firm, about 30 minutes.

for the ganache

Microwave 1½ ounces chopped milk chocolate, 2 tablespoons heavy cream, and pinch salt in bowl at 50 percent power, whisking frequently, until chocolate is melted, 30 seconds to 1 minute. Divide ganache evenly between tart shells, spreading into smooth, even layer with clean offset spatula. Refrigerate, uncovered, until set, about 30 minutes.
To serve, remove outer metal ring of tart pans, slide thin metal spatula between tarts and tart pan bottoms, and carefully slide tarts onto individual plates. Sprinkle with flake sea salt.