Preheat the oven to 350°F.
MAKE THE CRUST: In a food processor, pulse the chocolate cookies until ground into crumbs. Transfer the crumb mixture to a medium bowl and stir in the sugar, salt, and melted butter until well incorporated.
Press the mixture evenly into the bottom and sides of a 9-inch tart pan with a removable bottom. Bake until the crust is set, about 10 minutes. Let cool completely.
MAKE THE FILLING: Put the chocolate chips in a large bowl.
Heat the cream in a small saucepan over medium heat until it just comes to a simmer. Pour the cream over the chocolate bits and let the mixture sit for 1 minute to melt. Stir gently until the mixture is smooth.
In a separate bowl, lightly beat the eggs and vanilla. Whisk the egg mixture into the chocolate mixture until smooth, then pour the filling into the cooled tart shell.
Bake the tart until the edges begin to puff and the first crack appears—the center will still be jiggly—18 to 20 minutes. Let cool completely, until set.
MAKE THE GLAZE: Put the chocolate chips in a small bowl.
In a small saucepan, heat the cream until it simmers gently and then pour it over the chocolate. Let sit for 1 minute, then whisk until smooth. Pour over the tart and allow to set, about 20 minutes. Sprinkle with Maldon salt.
Cut into thin slices and serve.
