Lemon diamond cookies

INGREDIENTS:

14 oz BUTTER. softened slightly
7 oz SUGAR
17 oz AP FLOUR
zest from 1 LEMON
handful of LEMON BASIL (optional)
COARSE SUGAR for rolling
1 Egg yolk

PROCESS:
1. zest the lemon and using your fingers, rub zest into the sugar (this perfumes the sugar by releasing the zest oil into the sugar)
2. Chop the basil finely - it helps if you combine it with some of the sugar.
3. Using the paddle attachment, cream the butter.
4. Add the sugar, zest and basil and mix well.
5. Add the flour, but don’t over-mix. Stop as soon as it is mixed.
6. Ball the dough tightly and roll it into one or more cylinders. You want the roll to be tight. (I made this into more of a square log, because it's easier to slice.) Refrigerate until cold.
7. Remove logs and brush on egg yolk. Roll in course sugar (or sprinkle on).
8. Slice and bake at 325 degrees. Watch carefully because the yolk burns easily. You can try baking with 2 cookie sheets. These are meant to be crispy so they need to get a little color. They crisp up as they cool.
NOTES:
These are called diamonds because of the course sugar, not the shape.
The log is good to keep in the freezer for a last minute baking emergency. (ha) Add yolk and sugar right before baking.
You can use orange zest and a splash of grand marnier for a different flavor.
When slicing a round log, rotate the log one quarter turn before each slice. This helps the log maintain its shape. A square or rectangular log works too.