In a large bowl, cream together butter and sugar for about 1 minute.
Sift the flour. Then add 4 cups of flour to the butter mixture in 4 additions. Mix until the flour is just incorporated after each addition. Add more flour a few tablespoons at a time, until the dough comes together in big clumps and has a silky texture. (You can add up to 1 cup more flour. See note)
Turn dough out onto a pastry mat and knead for a minute. Divide dough into 4 balls, and place 2 balls each into two 9-inch x 13-inch pans.
Use hands to spread dough into an even layer. The dough should NOT be more than 1/2-inch thick. (Check this with a ruler, seriously!)
Place a piece of waxed paper over the cookie dough. Use a rolling pin or the back of a measuring cup to smooth the handprints from the top of the cookies by pressing on the dough over the waxed paper. Repeat with the other pan.
Use a sharp knife to score the dough into rectangles. (I get 36 cookies per pan = 6 rows and 6 columns.) Then use a fork to prick the top of the cookies 3 times each.
Bake for 30 minutes or until the cookies are set and the edges are just turning golden.
Remove from the oven to a cooling rack. Use the same knife to score the cookies again following the same lines. Allow to cool in pan completely before serving.
Notes
If you don't have salted butter on hand, you can substitute unsalted butter + 1 teaspoon salt. (1/4 teaspoon salt per 1/2 cup butter = 1 stick)
The first time I made this recipe the dough had a sandy texture and was super crumbly. The second time I made it (the exact same way) it was spot on. I recommend starting with less flour and adding more until the dough has the right consistency. The weather, heat of your kitchen, altitude, and other variables can affect the cookie dough. While it's a simple recipe it can be finicky.