I used the best quality butter I could, which is the same butter I use in my shortbread cookies. When your recipe calls for only a few ingredients, you'd better use the best! I'm sure French butter is very different from ours and Dorie does talk about the different butters and the ones she likes.
And, of course, as you can see from the photo, I made them into sandwich cookies, using a raspberry filling I found on Martha Stewart's site ( Once again, linking the recipe!).
Making these cookies was very similar to making the shortbread. They go together easily, then you chill the dough, roll them out and chill the dough again.
I put them onto parchment paper to bake but you could also try just sprinkling some granulated sugar onto the baking sheet without the parchment. I think because of all the butter,it shouldn't stick. Just remember to take your metal spatula and loosen them just after they come out of the oven because if they cool too long on the sheet they may be very difficult to remove in one piece.
I wound up really loving the thinner ones, the ones that were rolled out to 1/8" thickness. They were crunchier and I love the crunch! Dorie said to bake til still pale but I like them baked til they have a slight light brown color on the edges. Now, maybe that's not the correct French way to do it but, it's just my preference.
Other fillings, if you chose to make sandwich cookies, could be chocolate ganache, the mint or coffee filling Martha has recipes for, or how about a nice citrus filling like lemon or orange?