A simple stir-together recipe with a stunning final effect, these biscotti have a nutty crunch from semolina, while a bit of lemon enhances their flavor. They look their best dipped in a bright blueberry glaze.
Preheat the oven to 350°F. Line a baking sheet with parchment.
To make the dough: In a large bowl, stir together the melted butter, sugar, salt, baking powder, lemon zest, and vanilla; mix until well blended. Stir in the eggs one at a time. Add the flours, stirring until everything is well combined. Stir in the dried blueberries.
To shape: Divide the dough in half and shape each piece into a 10 1/2" x 4" log right on the prepared baking sheet, leaving 3" of space between them. Smooth the top with a wet spatula.
Bake for 25 to 30 minutes, until the center is firm when pressed. Remove from the oven and let cool for 30 minutes on the pan. Lower the oven temperature to 325°F.
Transfer the logs to a cutting board and spray or brush lightly with water. Use a serrated knife to cut into 1/2"-wide slices. Don’t press down on the knife; rather, draw it back and forth in a sawing motion until the slices are cut, to keep crumbling to a minimum.
Return the slices to the baking sheet standing up with 1/2" of space between them. Return to the oven and bake for 22 to 26 minutes, until golden. Remove from the oven and let cool on the pan.
To make the glaze: In a small saucepan, combine the blueberries, granulated sugar, and water. Bring to a boil and cook for 1 minute. Remove from the heat and strain the liquid from the berries; save the berries for another use.
In a medium bowl, combine the confectioners’ sugar, corn syrup, and 3 tablespoons of the blueberry juice. Stir in the lemon juice. Add more blueberry juice as needed to make the glaze the consistency of honey. It should fall off the spoon in a thick ribbon that disappears back into the bowl after a few seconds. Dip the cooled biscotti in the glaze.
Store biscotti, well wrapped, at room temperature for up to a week; freeze for longer storage.
