Combine graham cracker crumbs, flour, and salt in a bowl.

In another bowl, beat together butter, brown sugar, and vanilla extract until creamy and fluffy.

Add the dry ingredients to the creamed mixture and mix until a dough forms. Set aside.

Whisk together cocoa powder, white sugar, brown sugar, melted butter, vegetable oil, eggs, and vanilla extract until smooth.

In a separate bowl, whisk together flour, baking soda, and salt.

Combine the dry ingredients with the wet ingredients to form a soft dough.

Mix in the chocolate chips.

Preheat your oven to 350°F and line a baking sheet with parchment paper.

Use a cookie scoop to place balls of brownie cookie dough on the baking sheet, flattening them slightly. Space them apart (about 6 per sheet).

Shape the graham cookie dough into discs and place one on top of each brownie cookie.

Spoon marshmallow fluff onto each cookie.

Bake for 10 to 11 minutes, then sprinkle graham cracker crumbs on top of the marshmallow.

Let the cookies cool on the tray for 10 to 15 minutes before indulging in their gooey goodness!