Bittersweet Chocolate Tart with Salted Caramelized Pistachios

4 oz. (8 Tbs.) unsalted butter , melted

1/4 cup granulated sugar

1 tsp. finely grated orange zest

3/4 tsp. pure vanilla extract

tsp. table salt

4 1/2 oz. (1 cup) unbleached all-purpose flour For the Filling:

1 cup half-and-half

2 Tbs. granulated sugar

Pinch table salt

7 oz. semisweet chocolate (up to 64% cacao), coarsely chopped

1 large egg , lightly beaten

1 recipe Salted Caramelized Pistachio s

Fleur de sel or other flaky sea salt