1. Place flours, salt, and pepper in the bowl of a food processor; pulse to combine. Add cheese and butter; pulse until blended. Add egg and cream; process until ingredients are moist and well combined but a dough will not form around the blade, 15 to 20 seconds.

2. Place a piece of plastic wrap on work surface. Turn dough out onto plastic wrap; press together until it forms a cohesive dough. Divide dough into 2 equal pieces. Using the plastic wrap to assist you, form each piece of dough into two square 5 1/2-inch-by-1 1/2-inch logs. Rewrap each log separately, twisting ends to flatten. Transfer logs to freezer until chilled, 45 minutes to 1 hour.

3. Preheat oven to 375 degrees with a rack set in center. Line baking sheets with parchment paper; set aside.

4. Using a sharp knife with a thin blade, slice dough crosswise into 1/8-inch-thick squares, turning log after each cut to help maintain shape. Transfer squares to prepared baking sheets. Using a pastry brush, lightly brush each square with water and sprinkle with sea salt, if desired.

5. Transfer baking sheets to oven. Bake until crisp and golden around the edges, about 12 minutes. Transfer crackers to a wire rack to cool.