To make the sourdough graham cracker crust, combine the butter and sugar together until light and fluffy. Beat in one egg. Mix in the sourdough discard and vanilla extract.

In a separate bowl, combine the flour, graham cracker crumbs, baking soda and salt. To make graham cracker crumbs at home, put in a food processor or blender until a fine powder or smash in a ziplock baggie with a rolling pin or your hands.

Grease the bottom of a 9x13 pan. Press the sourdough graham cracker dough across the bottom. The layer will look flat and will increase in height as the bar cooks.

Poke holes in the bar with a fork and put into the oven. Cook at 350 for 8-10 minutes. The crust will begin to turn golden brown.

Make homemade marshmallow fluff in two steps. First, make soft peaks with the egg whites and cream of tartar while simultaneously heating the sugar mixture on the stove.

These steps can be completed simultaneously. It is important the you sugar mixture is hot when pouring it into the whipped egg whites to ensure it does not stick to the mixing while cooling.

To begin, allow two egg whites to warm on the countertop for 30 minutes. This will allow the egg mixture to form soft peaks quicker.

Separate the egg white from the yolk ensuring no egg yolk goes in the mixing bowl. Reserve the egg yolk for another recipe, if desired.

To the mixing bowl, add the cream of tartar. On a medium - high speed, whip the egg whites and cream of tartar until they form soft peaks.

This can take around 7-15 minutes depending on how quickly the mixture comes together. The speed for a Kitchenaid professional mixer is 6-8.

Soft peaks can be defined as putting your whisk attachment or a utensil into the bowl, flipping it over and the egg whites bend over on themselves, making a “soft peak”. They will not slide off and will hold shape. (If you need a visual, think of Alfalfa’s hair from The Little Rascals!).

While the mixer is running, combine the corn syrup, white sugar, water and salt in a pan on the stovetop. On a medium heat, allow the mixture to come to a boil. Once the temperature reaches 240 degrees, remove the pan from the heat.

Lower the speed of the mixer to low (speed 2 on a Kitchenaid).  Slowly and steadily, pour the sugar mixture into mixing bowl with the eggs. Pour the mixture between the side of the bowl and the whisk.

If the sugar mixture flies off the whisk and hits the side of the bowl the speed is going too fast. Once the sugar mixture is added, increase the speed of the mixer to medium (level 6 on a Kitchenaid) for 6-8 minutes.

The mixture will thicken in texture and become white in color. At this point, add the vanilla extract and turn on low until combined.

Add the marshmallow fluff to the top of the chocolate ganache layer. Spread carefully to ensure chocolate layer does not combine with marshmallow layer (unless looks are not important as the top will be toasted prior to serving).