1. Preheat Your Oven and Prepare Your Pans

Preheat your oven to 350°F (175°C) and grease and flour two 9-inch round cake pans. This helps ensure the cake comes out nice and easily. You can also line the bottom with parchment paper for extra insurance.

2. Mix the Dry Ingredients for the Cake

In a large mixing bowl, whisk together the flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt. Make sure everything is well combined. The cocoa powder gives the cake its rich chocolate flavor, and the baking soda and powder will help the cake rise beautifully.

3. Add the Wet Ingredients

In a separate bowl, whisk together the eggs, milk, vegetable oil, and vanilla extract. Add these wet ingredients to the dry mixture and stir until fully combined. The batter will be quite thick at this point, but don’t worry—that’s normal!

4. Incorporate the Boiling Water

Carefully pour in the boiling water. This step is key to making the cake moist and tender. The batter will be thin now, but it will bake into the most delicious, soft, chocolatey cake you’ve ever tasted. Stir everything together.

5. Bake the Cake Layers

Divide the batter evenly between the prepared cake pans and smooth the tops. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Don’t forget to rotate the pans halfway through baking for even cooking.

6. Cool the Cake Layers

Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely. You want them to be completely cool before frosting—this ensures the frosting won’t melt!

7. Make the Marshmallow Frosting

While the cakes are cooling, it’s time to make the marshmallow frosting. In a large bowl, beat together the softened butter and powdered sugar until light and fluffy. Add the marshmallow fluff, vanilla extract, and a pinch of salt. If the frosting feels too thick, add a tablespoon or two of heavy cream until you get the perfect spreadable consistency.

8. Prepare the Graham Cracker Crust

To make the graham cracker topping, mix together the graham cracker crumbs, melted butter, and brown sugar. Stir until the crumbs are evenly coated. This will give the cake a crunchy, crumbly topping that’s so reminiscent of traditional s’mores.

9. Assemble the Cake

Once the cake layers have cooled completely, place one layer of cake on a cake plate or serving platter. Spread a generous layer of marshmallow frosting on top, followed by a sprinkle of graham cracker crumbs. Place the second cake layer on top and spread the rest of the frosting over the top and sides of the cake.

10. Decorate the Cake

Sprinkle the remaining graham cracker crumbs over the top and sides of the cake. Then, add mini marshmallows and chocolate chips on top for that signature s’mores look. If you’re feeling extra indulgent, you can even lightly toast the marshmallows using a kitchen torch for that authentic s’mores experience.