Summarize this article in one sentence.
Beat the flour until the flour is just incorporated.   5 centimeters) thick.

Summary:
In a large mixing bowl, beat the butter, confectioner’s sugar, lemon zest and salt until the mixture is well combined, either using a stand mixer with a paddle attachment or a handheld mixer. Turn the mixer to low speed and add 1/2 cup of flour to the bowl. Continue adding the flour and mixing it in, 1/2 cup at a time, until all of the flour has been incorporated. Spoon the dough onto a large piece of plastic wrap. Pat the dough until it becomes a disc that is about 1" (2. Cover it and refrigerate the dough for 1 hour.