In a large bowl, mix the flours and stir in the salt.

Cut the chilled butter into lengthwise quarters and then into ½-inch cubes.

Add the butter cubes to the flour mixture.

Using your fingers, flatten each cube into flakes while combining them with the flour.

Refrigerate the mixture for 10 minutes, ensuring the butter remains firm.

Add the ice-cold water and stir until the dough loosely holds together.

Transfer the dough onto a lightly floured work surface and pat it into an 18 x 8-inch rectangle.

Sprinkle the top with flour.

Fold the dough lengthwise in thirds, similar to folding a business letter.

After folding, flour the work surface again and the top of the dough.

Roll out the dough with a rolling pin to maintain the previous size, keeping the folded sides as the width and the open ends as the length.

Work swiftly; refrigerate briefly if the butter softens.

Fold the dough a second time in the same manner, roll it out again, and repeat this process two more times (for a total of four times).

Ensure surfaces are floured as needed, and always end with the dough folded.

Cover the dough with plastic wrap and refrigerate it for 40 minutes.

Roll and fold it twice more.

The dough is now ready to use or can be stored in the refrigerator or freezer for future use.