01 -
Cream butter and powdered sugar on low speed using a stand mixer fitted with a paddle attachment.
02 -
Add egg and mix briefly, then incorporate flours, salt, and pecans; mix until just combined.
03 -
Shape dough into a flat disk and refrigerate for 30 minutes if it feels too sticky to handle.
04 -
Roll dough on a floured surface to a 12-inch circle, transfer it to a 9.5-inch tart pan, pressing into edges; trim excess.
05 -
Freeze the tart shell for 30 to 60 minutes to ensure it holds shape during baking.
06 -
Preheat oven to 350°F. Line tart shell with parchment paper and pie weights. Bake for 24-28 minutes, removing weights for the last 5 minutes. Cool completely.
07 -
Melt butter and sugar over medium heat in a heavy-bottom saucepan, stirring steadily until sugar is amber and smooth, approximately 5-7 minutes.
08 -
Simmer heavy cream in a separate small saucepan and keep warm.
09 -
Remove caramel from heat and slowly whisk in warm cream until smooth and fully combined. Stir in fleur de sel and ground cinnamon. Cool for 15 minutes.
10 -
Pour caramel filling into the cooled tart crust. Refrigerate for 1 hour before adding mousse.
11 -
Sprinkle gelatin over cold water in a small bowl and let it bloom for 5 minutes.
12 -
Heat 1/4 cup heavy cream, stir in bloomed gelatin until fully dissolved.
13 -
Pour hot cream and gelatin mixture over chopped white chocolate; stir until smooth and let cool to room temperature.
14 -
Whip remaining 3/4 cup heavy cream with granulated sugar to soft peaks.
15 -
Gently fold whipped cream into the cooled white chocolate mixture until incorporated.
16 -
Pour white chocolate mousse over chilled caramel layer. Refrigerate tart for 2 hours before serving.