For custard: In a 3½-quart saucepan, whisk together milk, egg yolks, sugar, and cornstarch. Add vanilla bean and reserved seeds and salt. Cook over medium-low heat, whisking constantly, until custard simmers and thickens, 8 to 10 minutes. Remove from heat; discard vanilla bean. Transfer to a bowl, and press a sheet of plastic wrap directly onto surface of custard. Refrigerate until cold, about 4 hours.

Preheat oven to 350° F. Spray a 14x4-inch tart pan with baking spray with flour.

For crust: In a medium bowl, stir together crushed cones, brown sugar, melted butter, and salt. Press mixture into bottom and up sides of prepared pan.

Bake until golden brown, 8 to 10 minutes. Let cool completely.

For topping: Place chocolate in a small bowl. In a small saucepan, heat cream over medium-high heat until bubbling. Pour hot cream over chocolate (do not stir). Cover and let stand for 5 minutes. Whisk until smooth. Dip cone pieces halfway in chocolate, and place on a sheet of wax paper to let set. Pour remaining chocolate into prepared crust. Refrigerate until set. Pour custard over chocolate. Top with peanuts and waffle cone pieces.