For the crust you'll need:
1 stick unsalted butter, softened
1 1/4 cups coarsely crushed thin pretzels (3 1/2 ounces)
3/4 cup confectioners’ sugar
1/2 cup all-purpose flour
1 large egg
2 ounces bittersweet chocolate, melted
Preheat the oven to 350°. Roll out the dough between the sheets of plastic wrap to a 12-inch round. Peel off the top sheet and invert the dough over a 10-inch fluted tart pan with a removable bottom. Press the dough into the corners and patch any tears. Trim the overhanging dough and refrigerate the shell for 30 minutes or until firm.
Line the shell with parchment paper and fill with pie weights (I used split peas & foil). Bake for about 30 minutes, until nearly set. Remove the parchment and weights and bake for 10 to 15 minutes longer, until the tart shell is firm; cover the edge with foil if it darkens too much. Let the shell cool completely. Brush the melted chocolate over the bottom and up the side and refrigerate for 10 minutes, until set.
Meanwhile, make the filling:
1 1/2 cups heavy cream
3/4 pound milk chocolate, chopped
Maldon sea salt, crushed pretzels and crème fraîche, for serving
In a medium saucepan, bring the cream to a simmer. Off the heat, add the milk chocolate and let stand for 5 minutes. Whisk until smooth. Transfer the filling to a bowl and let cool to room temperature, about 1 hour.
Pour the filling into the shell and refrigerate until set, at least 4 hours. Sprinkle lightly with sea salt and crushed pretzels. Cut into wedges, top with crème fraîche; serve.