Preheat the oven to 375˚F, and line a baking sheet with parchment paper.
Place the cheese, butter, flour, and salt into a food processor. Pulse, for 5 seconds at a time, about five or six times, until the dough becomes coarse crumbs.
Slowly add the milk, 1 tablespoon at a time, with the food processor on, until the dough becomes a ball.
Divide the dough into two balls, and refrigerate for 15 minutes. Remove one dough ball from the refrigerator, and roll it on a floured board with a floured rolling pin until it is about ⅛ inch thick.
Cut the dough into 1-inch squares with a sharp knife or pizza cutter. You can put a bit of flour on the blade of the knife to keep it from sticking. Use a toothpick or skewer to poke a hole in the center of each cracker.
Place the crackers at least ¼ inch apart on the baking sheet. Repeat the process with a second ball of dough.
Bake for 12 to 15 minutes, with the rack placed in the middle of your oven, until the edges are just starting to brown. They might puff up too. If you are baking two pans at the same time, swap/rotate the pans halfway through.
Place the baking sheet on a rack, and let the crackers cool completely. Eat or store in a covered container for up to 3 days.