Step 1Heat the oven to 350 degrees. Lightly butter an 8-inch cake pan and line with parchment. Butter the parchment and flour the pan with cocoa powder, shaking out the excess.
Step 2Sift together the flour, cocoa, baking soda and powder, and salt. Set aside.
Step 3In a large bowl, beat together the egg and sugar until thickened and lemon-colored, 3 to 5 minutes. Slowly beat in the vegetable oil. Add the dry ingredients and buttermilk in thirds, alternating between each, and scraping down the bowl once or twice. Beat in the coffee and vanilla to form a thin batter and pour into the prepared pan.
Step 4Bake until the cake is set and a toothpick inserted in the center comes out clean, about 40 minutes, rotating the cake halfway though for even baking. Invert the cake onto a cooling rack, peel off the paper and cool completely. Cover the cake completely with plastic wrap and freeze until firm.
Step 5Using a serrated knife, carefully split the firm cake into three thin layers. Using a round cutter, cut 18 circles. The circles can be made up to 1 month in advance; cover tightly and freeze the layers if not using immediately, giving them time to thaw before assembling the final dessert.
Step 1Place both flours, sugar, baking powder, baking soda, salt and cinnamon into the bowl of a food processor and pulse several times to combine. Add the butter and pulse until the mixture resembles cornmeal. Add the molasses, honey, milk and vanilla extract and process until the dough forms a ball, approximately 1 minute. Press the ball into a 1/2-inch thick disk, wrap in plastic wrap, and refrigerate for 30 minutes.
Step 2Preheat the oven to 350 degrees.
Step 3Unwrap the chilled dough and place it onto a large piece of parchment paper and top with a second sheet of parchment paper. Roll the dough out until it is 1/16" inch thick. Slide the rolled dough and parchment paper onto a half sheet pan. Remove the top sheet of parchment paper and cut the dough, using a rolling pizza cutter into 2-inch square pieces, by making vertical and then horizontal cuts all the way across the dough.
Step 4Trim off any excess. Using a fork, poke holes all over the top of the dough. Leave the crackers on the pan and bake on the middle rack of the oven for approximately 16 to 20 minutes or until the edges just start to turn golden dark. Remove from the oven, set the sheet pan with the crackers on a cooling rack and allow to cool completely. Once completely cool, break into individual crackers. This makes about 2 dozen crackers, depending on size; they will keep stored in an airtight container for up to 2 weeks.
Step 1Stir together the sugar, corn syrup, water and salt in a small saucepan over high heat. Bring to a boil, stirring occasionally, until the mixture reaches 240°F on a candy/fat thermometer.
Step 2Place the egg whites and cream of tartar in the bowl of a stand mixer fitted with a whisk attachment. Start whipping the egg whites to soft peaks on medium speed. (The goal is to have the egg whites whipped and ready, waiting for your syrup to be drizzled in. If they're whipping faster than your syrup is coming to temperature, just stop the mixer until the syrup is ready.)
Step 3When the sugar syrup is heated, reduce the mixer speed and slowly drizzle about 2 tablespoons of syrup into the egg whites to warm them. (If you add too much syrup at once, the whites will scramble.) Slowly drizzle in the rest of the syrup. Increase the mixer speed and whip until the marshmallow crème is stiff and glossy, about 7 minutes, then whip in the vanilla. This makes a generous 2 cups marshmallow fluff.
Step 1To assemble each dessert, place 1 chocolate cake layer in a glass or narrow serving dish. Top with about 2 tablespoons ganache, then repeat until you have 3 layers of cake and 2 layers of ganache. Top with a dollop of marshmallow fluff. Caramelize the marshmallow using a kitchen torch and serve with graham crackers on the side. Repeat to assemble the remaining desserts.