Preheat the oven to 325 F. Butter a 12-by-8-inch rimmed baking sheet and line with parchment paper, leaving a 1-inch overhang on long sides. Whisk together flour and salt in a small bowl; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat butter until fluffy on medium speed, 3 to 4 minutes. Add confectioner’s sugar and honey; continue to beat until very light and fluffy, about 2 minutes, scraping down the sides of the bowl as needed. Add flour mixture, and beat on low speed, scraping down sides occasionally, until just incorporated. (It should have the consistency of soft cookie dough)
Using a small offset spatula, evenly spread dough in prepared baking sheet. Chill in the freezer or refrigerator until dough is firm, about 15 minutes.
Prick dough all over with a fork. Bake, rotating sheet halfway through, until shortbread is golden brown, 40 to 45 minutes. Transfer to a wire rack and immediately sprinkle with confectioner’s sugar. The more sugar on top, the better! While still hot, use a large knife to cut shortbread into 4-by-1-inch pieces. Cool completely in the pan. Shortbread can be kept in an airtight container at room temperature for up to 1 week.