Preheat oven to 300°F Whisk together flour, salt, baking powder, and rosemary in a bowl.
Mix together butter, honey, and confectioners sugar with elec.
mixer at low speed, then add flour mixture and mix until dough resembles coarse meal (with some small, roughly pea-sized butter lumps).
Gather dough,and transfer to an 8X8 square pan.
Knead dough out into pan, making sure it has come together.
Using tines of a fork, make marks around the edge of the pan, and also across where cookies will be cut when baked.
In each square, arrange rosemary sprigs (if using) decoratively on top of dough, pressing lightly to help adhere, and sprinkle dough with 1/2 tablespoon granulated sugar.
Bake shortbread in middle of oven until golden brown, 35-40 minutes.
Cool 5 minutes, then cut along score marks, remove from pan, and allow to cool completely.
Cooks' note: • Shortbread keeps in an airtight container at room temperature 1 week.
