Attach the shredding attachment to the food processor and shred the cheese. (Alternately, grate on the large hole of a box grater.)
Add the cheese, flour, baking powder and 1/2 teaspoon kosher salt to the bowl of a food processor. Process until combined, about 30 seconds.
With the food processor running, stream in the melted butter and continue processing until the dough forms a ball.
Lightly flour your work surface. Turn out the dough onto the flour and shape it into a 1-inch-thick disk. Wrap the disk in plastic wrap and refrigerate it for a minimum of 1 hour and up to 2 days. (If the dough has been chilling longer than an hour, let it sit at room temperature for about 20 minutes before rolling so it’s easier to work with.)
When ready to bake, preheat the oven to 350°F. Line two baking sheets with parchment paper.
Lightly flour your work surface then use a rolling pin to roll out the dough until it is 1/4-inch-thick. Use a knife (or fluted ravioli cutter) to cut out 1-inch squares. (Scraps can be re-rolled.) Transfer the crackers onto the prepared baking sheets then make a small hole in the center of each cracker using the bottom of a bamboo skewer. Sprinkle with salt (optional).
Bake the crackers until they are golden brown on the edges, 12 to 15 minutes. Remove them from the oven and let them cool completely on the baking sheet before serving.