Makes about 8 dozen
Combine flours and salt in a food processor and pulse for 30 seconds. Add butter and pulse for another 30 seconds or until mixture looks crumbly. Add 1 cup warm water in a slow and steady stream and process until dough comes together to form a ball. Remove dough from food processor and press into a disc. Wrap disc in plastic wrap and refrigerate 30 minutes.
Preheat oven to 500 degrees with a rack set in the middle.
Divide dough into 8 pieces. Working with one piece of dough at a time, on a lightly floured work surface, flatten dough with the palm of your hand. Using a rolling pin, roll the dough as thinly as possible. (Best results will be achieved if the dough is rolled to a consistent thickness so that all parts of the crackers cook at the same rate.) Using a knife or a pizza cutter, cut crackers into rectangles about 3 1/2 inches long and 1 1/2 inches wide (or in any shape you prefer). Place crackers on a baking sheet and brush lightly with olive oil. Sprinkle each cracker lightly with Parmesan, coarse salt, and pepper. Bake crackers for 10 to 12 minutes or until they are completely crisp and golden brown. Allow to cool on their pans or on wire cooling racks. Repeat until all dough is used.