Preheat your oven to 300°F (150°C) and line cake pans with parchment paper. Grease the sides lightly.

In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, and salt until well combined.

Add eggs, milk, oil, and vanilla extract. Mix until smooth and fully incorporated.

Slowly pour in hot water while mixing. The batter will be thin—this is normal and ensures a moist cake.

Divide batter evenly among the prepared pans.

Bake for 30–35 minutes or until a toothpick inserted comes out with a few moist crumbs.

Remove cakes and let them cool completely on a rack.

Increase oven temperature to 350°F (175°C).

In a bowl, mix graham cracker crumbs, sugar, and melted butter.

Spread mixture onto a lined baking sheet and bake for 8–10 minutes until lightly golden.

Let cool completely to form crunchy bits.

To prepare frosting, beat butter until creamy and smooth.

Add marshmallow fluff and mix until fully combined.

Gradually add powdered sugar and beat until fluffy.

Stir in vanilla extract.

Fold in toasted mini marshmallows for added flavor and texture.

For ganache, heat heavy cream until just steaming (not boiling).

Pour over chocolate chips and let sit for 3–5 minutes.

Whisk until smooth and glossy. Allow to cool slightly.

To assemble, place one cake layer on a serving plate.

Spread a thin layer of ganache over the cake.

Add a layer of marshmallow frosting on top.

Sprinkle graham cracker crunch evenly.

Place the second cake layer and repeat the process.

Add the final cake layer on top.

Apply a crumb coat of frosting and chill for 20–30 minutes.

Frost the entire cake with remaining marshmallow frosting.

Press graham cracker crumbs around the bottom edges.

Pour ganache over the top, allowing it to drip down the sides.

Decorate with toasted marshmallows on top.

Chill for 30 minutes before slicing to set layers properly.

Slice and serve for best texture and presentation.