I use crushed bits of our homemade Butter Toffee in this recipe. If you have store bought toffee, you can substitute an equal amount with delicious results.This recipe incorporates my homemade substitution for cake flour. Cake flour's lower protein content helps to create a more tender cookie. A few years ago, I discovered that I could easily make my own cake flour substitute using All-purpose flour and cornstarch. If you prefer, you can use 2¾ cup of store bought, premixed cake flour or simply use All-purpose flour instead.