Step 1

Preheat your oven to 375 degrees F. Spray three 8-inch or four 6-inch round cake pans with non-stick spray and then line with parchment. Spray again. Set aside.

Step 2

In a medium sized bowl combine the graham cracker crumbs, melted butter and sugar. Stir until all the graham cracker crumbs are damped by the melted butter.

Step 3

Divide evenly between the three pans and press down firmly with your hand or the back of a spoon.

Step 4

Bake for 5 minutes. Let cool while you make the chocolate cake batter.

Step 5

Preheat the oven to 325 degrees F.

Step 6

Combine the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.

Step 7

In another bowl, combine the buttermilk, oil, eggs, water and vanilla.

Step 8

With the mixer on low speed, slowly add the wet ingredients to the dry, scraping the bottom of the bowl with a rubber spatula.

Step 9

Pour the batter into the prepared pans (about 12 ounces in each 6-inch pan or 15 ounces in each 8-inch pan), over the cooked graham cracker crusts and bake for 25 to 30 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumsb on it.

Step 10

Cool in the pans for 10 minutes, then turn them out onto a cooling rack and cool completely.

Step 11

Wrap in plastic wrap and chill until ready to use.

Step 12

Place the marshmallows on a cookie sheet lined with parchment paper and sprayed with nonstick cooking spray. Place on the middle rack of the oven, and broil the marshmallows until golden brown on top, about 30-60 seconds. Keep your eye on them!

Step 13

Remove the pan from the oven and gently turn the marshmallows over and broil them again until they are golden brown on the other side.

Step 14

In the bowl of a stand mixer fitted with the paddle attachment, combine the butter and powdered sugar and beat on low until blended. Add the vanilla and mix on medium speed for about three minutes

Step 15

With the mixer on low speed, add the marshmallow cream and (cooled) toasted marshmallows, and mix for about one minute.

Step 16

In a microwave safe bowl, pour the cream over the chocolate chips and heat for about 45-60 seconds. Stir, and if needed, heat for another 30 seconds to melt the chocolate chips completely. Let cool to room temperature before using.

Step 17

In the bowl of a standing mixer, whisk the eggs and salt until fluffy and frothy.

Step 18

Meanwhile, heat the sugar, corn syrup, water and vanilla paste. Heat over medium flame until the sugar is dissolved and just simmering, about 5 minutes.

Step 19

With the mixer on medium speed, add a tiny bit of the hot sugar mixture to the egg whites at a time. (Temper the eggs - don't scramble the them)

Step 20

Eventually, all of the sugar will be added and then turn the mixer up to high. Beat the mixture on high for about 5 minutes or until very stiff and shiny.

Step 21

Best used right away.

Step 22

Heat the cream until nearly boiling in a microwave safe bowl. Pour the hot cream over the chocolate chips and stir until the chips are melted and the mixture is smooth. Set aside.

Step 23

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter for about 2 minutes on medium-high speed.

Step 24

With the mixer on low speed, add the ganache. Scrape down the sides and bottom of the bowl and then mix on medium-high speed for about a minute, until the mixture is smooth.

Step 25

Gradually add the powdered sugar, one cup at a time, followed by the vanilla and salt.

Step 26

Buttercream can be store in an airtight container in the refrigerator for a week.

Step 27

When you're ready to frost the cake, bring the frosting back to room temperature and mix by hand with a wooden spoon to push out all of the air pockets.

Step 28

Level each chocolate cake layer, if needed, and then place the first cake layer, graham cracker side down, on a cake board.

Step 29

Spread half of the chocolate ganache on the cake layer and then freeze for 5 to 10 minutes to set the ganache a little.

Step 30

Carefully spread half of the toasted marshmallow filling over the chocolate ganache and repeat step 2 and 3 for the second cake layer.

Step 31

Place the final cake layer, graham cracker side down, on top and cover with a crumb coat layer of the chocolate frosting. Freeze the cake for 10 to 15 minutes to set the crumb coat.

Step 32

Finish frosting the cake with the chocolate frosting and then decorate the top of the cake with the marshmallow fluff, toasting with a kitchen torch, if desired.