12sheets of graham crackers4 crackers per sheet (when roughly crumbled, about 2 cups)
4tablespoonsbuttermelted
Dash of salt
for the chocolate cake:
2cups(14 ounces )sugar
2cups(8 1/2 ounces) King Arthur Unbleached All-Purpose Flour
2tablespoons(3/8 ounce) Instant ClearJel® or cornstarch
3/4cup(2 1/4 ounces) Double-Dutch Dark Cocoa or Dutch-process cocoa
2teaspoonsbaking powder
2teaspoonsespresso powder
1/2teaspoonbaking soda
1teaspoonsalt
4large eggs
3/4cupvegetable oil
2teaspoonsvanilla extract
1/2cupwater
1/2cupof your favorite dark chocolatechopped and divided (optional)
for the marshmallow topping
16large campfire-style marshmallowsdivided (4 to a jar)
or
4extra large gourmet marshmallowsthe kind that come boxed and are cut in large rectangles
Instructions
Preheat oven to 350°F
make the crust
Pulverize the graham crackers in a food processor. Remove any large chunks that escaped the blades. Dump the crumbs in a bowl and drizzle with about 3/4ths of the melted butter. Add salt, and stir until well combined. The crumbs should stay in place when pressed or squeezed. If still crumbly, add the remaining butter and stir. Divide evenly among the four jars and use the blunt end of a tool or handle to tamp the crumbs firmly into place.
make the cake
Briefly whisk together the dry ingredients. Add the eggs, oil, and vanilla, and beat until smooth. Gradually add the water, beating until smooth. The batter will be very loose. Spoon or pour into the jars, dividing as evenly as possible. Top cake batter with chopped chocolate, if using.
Place jars in a large pan and add about an inch of water (a regular 9 x 13" cake pan works great here). (The water bath will help keep your glass jars from cracking.) Place in preheated oven.
Bake 40 - 50 minutes. If under-baking, use a instant-read thermometer to check the internal temperature at the center of the cake. It should register at least 160°F. If baking until set, a cake tester inserted into the center should come out clean. Allow jars to cool in the water bath for 15 minutes.
If serving right away, leave the jars in the water bath, and add 4 marshmallows to each jar (be careful - rims are hot!). Return pan to oven and heat for five minutes (marshmallows should begin to melt). Turn off the oven. Move the oven rack and pan to a position about 3 inches away from broiler units. Turn broiler to high, and heat until marshmallows are just toasted (don't walk away - this happens pretty quickly).
Remove pan from oven, and carefully move jars to a heat resistance surface to cool for 10 minutes. Jars might still be hot, so serve with a kicky cloth napkin or towel and a long spoon.
If saving until later, remove the jars from the water bath after their initial 15 minute rest, and allow to cool completely. At this point, you can either add the marshmallows to the jar (if they'll fit with the lid) or wait until you're ready to serve. Place lids on the jars and store at room temperature for up to three days.
To serve the make-ahead versions, remove the lids and add the marshmallows, if necessary. Then you can either reheat the jars in a preheated 350°F oven for 10 minutes, and finish off under the broiler, or — and this is much easier — use the microwave to heat each jar for 30 to 60 seconds until the marshmallows melt and puff up. Then toast under the broiler for a few minutes.
Notes
adapted (to cut the cake recipe in half) from King Arthur Flour. This recipe includes a delicious chocolate ganache (the "filling"), if you'd rather use that than the cake.