To make these sourdough s'mores bars without an additional fermentation period, follow these steps.
First, combine the butter and sugar together until light and fluffy. Add the eggs one at a time, beating until combined. Next, 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, place them in a ziplock baggie and smash with your hands or a rolling pin. Alternatively, add them into a food processor or blender until they become a fine powder. You can leave some small pea sized pieces if you prefer texture within your dough.
Add the dry ingredients to the wet ingredients by stirring them in.
Grease a 8x8 pan or line with parchment paper. Reserve half a cup (1/2 cup of the cookie dough to the side for the topping.
Place the remainder of the dough on the bottom of the pan and press down with your fingers or a rubber spatula.
Spread a layer of marshmallow fluff across the dough. Sprinkle the chocolate chips across the top.
Place dollops of the graham cracker cookie dough on top of the pan.
Bake for 20-25 minutes. If the crust seems done but the fluff is not golden in color use a torch to light the top of place under the broiler for 2-4 minutes.
These taste delicious warm but are even better the next day.
Long Fermentation Timeline
To follow a long fermentation period, make the graham cracker cookie crust as outlined above. Cover with plastic wrap and press down firmly to ensure the bars do not dry out. Allow them to sit on the counter to meet your fermentation goals (typically 4-12 hours).
If you would like to ferment the dough longer, place it within the refrigerator for up to 24 hours. When you are ready to bake, pull the dough out 15-30 minutes prior to baking. Assemble as outlined above.