Preheat oven to 120°C 250°F.
Line a 12x18 inch cookie sheet with parchment paper.
**Note: cookie sheet must be at least 1/2 inch deep. **
In a microwave safe container warm butter on high for 30 seconds to soften it.
Place butter in a mixing bowl. Add sugar to butter and beat until well combined.
Slowly add flour one cup at a time mixing on medium speed until well combined. The fifth cup of flour may need to be kneaded in by hand but all five cups must go in. The mixture will resemble coarse crumbs. Press evenly into prepared pan. Don’t be afraid to pound it into shape.
Using a sharp knife score the pressed dough into squares. Pierce each square twice with a fork.
Bake in preheated oven for one hour. Remove from oven and immediately re-score the squares.
Cool completely in pan. To store, place in airtight containers between layers of waxed paper.
Makes approx. 30 cookies depending on how you cut them.