Preheat oven to 350 degrees. Process graham crackers, sugar, and salt in a food processor until finely ground. Transfer to a bowl, and stir in melted butter. Mix until combined.

Pour mixture into a 9-inch cake ring or spring form pan set on a parchment-lined baking sheet. Press crumbs to form an even layer on bottom and sides of the pan. Bake until crust starts to turn golden, about 15 minutes. Let cool entirely on sheet on a wire rack. 

 Melt 10 ounces of milk chocolate in a large heatproof bowl set over a pan of simmering water; keep warm. Meanwhile, bring cream to a simmer in a medium saucepan over high heat; remove from heat. Whisk 1/4 cup hot cream into the beaten egg yolks, then whisk the yolk mixture into the remaining cream in the saucepan. Whisk cream mixture into the melted chocolate, and set the ganache aside. 

Coarsely chop remaining 5 ounces bittersweet chocolate, and transfer to a large bowl. Toss in 2 cups mini marshmallows and 1 cup whole toasted almonds. Scatter mixture all over the bottom of cooled crust. Reserve 1 cup ganache for topping, and pour the rest evenly on top of the filling (do not overfill the crust). Refrigerate tart, uncovered, until firm, about 1 hour. Meanwhile, cover reserved ganache with plastic wrap, and set aside at room temperature.