Blend the Cheddar, Parmesan, butter, and salt in the bowl of a stand mixer fitted with the paddle attachment on medium-low speed, or pulse the ingredients in the bowl of a food processor fitted with the blade attachment until soft and homogenous.

Add the flour and mix on low speed/pulse to combine; the dough will be dry and pebbly.

Slowly add the water (through the feed tube if using a food processor) and continue to mix/pulse as the dough coalesces into a mass. Depending on the cheese used and the humidity levels when you're making the Cheez-Its, you might only need a small dribble of water or the full 2 tablespoons.

Pat the dough into a disk, wrap tightly with waxed paper, and refrigerate for at least an hour.

Preheat the oven to 375 degrees Fahrenheit. Line two baking sheets with parchment paper or Silpat liners.

Divide the dough into two pieces and roll each into a very thin (1/8 inch or less) 10- by 12-inch rectangle. Using a fluted pastry cutter or a pizza cutter, cut the rectangles into 1-inch squares, then transfer to the baking sheets. Use the tip of a chopstick or a toothpick to punch a hole into the center of each square.

Bake for 12-15 minutes or until puffed and browning at the edges. Watch carefully, as the crackers will go from golden to burnt in the blink of an eye.

Immediately move the crackers to racks to cool. Cheez-Its will keep at room temperature in an airtight container for up to a week.