In a stand mixer fitted with a dough hook attachment, combine the flour, eggs, softened butter, salt, and 1 teaspoon of lemon zest. Beat on medium speed until the mixture resembles coarse crumbs, about 1 minute. Then, with the mixer on low speed, slowly pour in the milk mixture until fully incorporated. Increase the speed to medium-low and continue to beat until a smooth, elastic dough forms, approximately 8 to 12 minutes. If the dough is too sticky, add more flour, 1 tablespoon at a time, until it reaches the desired consistency.