In the bowl of a stand mixer or using a hand mixer, beat the butter with the sugar until light and fluffy. Add the egg and mix until combined, scraping down the sides and bottom to make sure it is well incorporated.
In a separate medium bowl, combine the all-purpose flour, semolina flour, rosemary, orange zest and salt. Slowly add the dry ingredients to the butter and sugar with the mixer on low. Mix just until incorporated. Add the pignoli and stir to combine.
Divide the dough into 2 parts. Roll each into a log about 10 inches long and 2 inches in diameter. Wrap in plastic and refrigerate at least 1 hour and up to overnight.
When ready to bake, preheat the oven to 350 degrees F. Line 2 sheet pans with parchment paper. Slice one cookie dough log into 1/4-inch-thick rounds. Place on the prepared sheet pans, leaving about 1 inch of space between the cookies. Bake for 12 minutes, rotating the pans halfway through; the cookies should be deep golden brown on the bottom and look dry on top. Remove from the pans and cool on wire racks. Repeat with the second log of dough.
The cookie dough can be made, formed into logs and frozen for up to 1 month. Thaw in the refrigerator before baking.
Recipe courtesy of Gabriele Corcos and Debi Mazar