In the bowl of a stand mixer fitted with a dough hook, combine flour, salt, sourdough discard, and butter. Mix on low speed until combined. Increase the speed to medium until a smooth dough forms.
Stretch out a piece of plastic wrap, place the dough on top, and press out into a square about ½ inches thick. This will make rolling easier. Refrigerate for 2-8 hours or overnight.
When you are ready to roll, take the dough from the fridge and set it aside.
Preheat the oven to 350°F convection (with the fan) or 375°F conventional (no fan). Convection will make better crackers if you have that option.
Line three sheet pans with a piece of parchment paper and brush with olive oil.
Lightly flour a work surface and a rolling pin. Quarter the dough using a knife or bench scraper and roll out one piece at a time as thin as you can, aiming for 2mm.
Use a sharp knife, pizza cutter or pie dough wheel to cut the dough to your desired size.
Place the cut dough on prepared baking sheets. Brush the tops of the crackers with more oil and sprinkle with Maldon, everything bagel seasoning, or other toppings.
Bake the crackers in the preheated oven until light golden brown, checking them every 3 minutes and rotating them. Allow to cool before serving or storing.
