Preheat oven to 275 degrees. Butter five 5 3/4-by-3 1/4-inch loaf pans; set aside. Sift flour and salt into a bowl.
Place butter in bowl of an electric mixer fitted with the paddle attachment. Beat on medium speed until light and fluffy, 3 to 5 minutes. Add sugar, and continue to beat until very light in color and fluffy, about 2 minutes more, occasionally scraping down the sides of the bowl with a spatula. Add vanilla. Add reserved flour mixture, and combine on low speed, scraping sides with spatula if necessary, until flour is just incorporated and dough sticks together when squeezed with fingers. Do not overmix.
Divide dough evenly into prepared pans, spreading it about 1 1/4 inches thick. Smooth tops with fingers. Decorate by using a skewer to prick holes in the top to create a pattern or word. Bake until firm and just starting to color, about 2 hours. It may be necessary to re-prick the design in the loaf as soon as it comes out of the oven, to help keep holes uniform. Remove bricks from pans, transfer to a cooling rack, and let cool to room temperature. Slice to serve.
Store in airtight container for three weeks.