Line a 9x13” baking pan with parchment paper. Preheat oven to 350 degrees.
Make the graham cracker layer: pulse flour, brown sugar, baking soda, and salt in your food processor. Add butter and pulse until the mixture is crumbly. Whisk honey, milk, and vanilla in a separate bowl. Add to the flour mixture and pulse until dough comes together in a ball. Press into prepared pan. Chill until ready to use.
Make the cheesecake layer: beat egg, fluff, and cream cheese with a hand mixer. Pour over graham layer. Return to refrigerator until brownie layer is complete.
Make the brownies: whisk together flour, baking powder, salt, and coffee. Set aside. Place butter and chocolate in a heat-proof bowl over a pot of simmering water (do not let the water touch the bowl). Stir until the butter and chocolate are melted together. Let cool for a few minutes, then whisk in eggs, one at a time. Whisk in vanilla. Add flour mixture and stir until combined. Pour over marshmallow cheesecake layer.
Bake for 40-45 minutes until a toothpick comes out almost clean. The center will still be a little soft but you will be able to tell that the edges are done because the cheesecake that pokes through is browned. Cool completely before cutting.