For crust: In the work bowl of a food processor, pulse graham cereal until finely ground. Add melted butter, egg white, and salt, pulsing until combined. Using the bottom of a measuring cup, press mixture into bottom and up sides of a 9-inch pie plate.
Bake until firm, about 12 minutes. Let cool. Leave oven on.
For filling: In the top of a double boiler, place butter and chocolate. Cook over simmering water, whisking frequently, until melted, about 10 minutes. Remove from heat. Whisk in sugars, eggs, and vanilla until smooth.
In a medium bowl, whisk together flour, baking powder, and salt. Whisk flour mixture into chocolate mixture until combined. Spread batter into prepared crust.
Bake until center is just set, about 35 minutes. Top with marshmallows; bake until marshmallows are lightly browned, about 10 minutes more. Let cool on a wire rack for 1 hour. Garnish with cinnamon cereal, if desired.
Notes
* We used Golden Grahams Cereal and Cinnamon Toast Crunch Cereal.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/honey-graham-smores-pie/