4 1/2 oz parmigiano-reggiano cheese, finely grated (2 1/4 c) .
1 c whole milk .
3/4 c butter, cold & unsalted & cut into 1/2-inch cubes .
4 c all-purpose flour, plus extra
Directions
Step #1 Put oven racks in upper & lower thirds of oven & preheat your trusty oven to 350°F.
Step #2 Whisk together flour, salt, 2 c cheese, baking powder, & 1 tbsp ground black pepper In a large-ish bowl.
Step #3 Blend in butter until mixture resembles coarse meal.
Step #4 Whisk 3 eggs with milk & add to flour mixture, stirring with a fork until a soft dough forms.
Step #5 Turn dough out onto a lightly floured surface & quarter dough.
Step #6 Using well-floured hands, form each piece into a slightly flattened 12-inch-long log (about 2 inches wide & 3/4 inch high).
Step #7 Transfer logs to 2 ungreased large baking sheets, arranging logs about 3 inches apart.
Step #8 Whisk remaining egg & brush some over logs, then sprinkle tops of logs evenly with remaining 1/4 c cheese & 1/2 tbsp ground pepper.
Step #9 Bake, until logs are pale golden & firm, rotating sheets 180 degrees & switching position of sheets halfway through baking, about 30 mins total.
Step #10 Cool logs to warm on sheets on a rack, about 10 mins.
Step #11 Reduce oven temperature to 300°F.
Step #12 Carefully transfer 1 warm log to a cutting board & cut diagonally into 1/2-inch-thick slices with a serrated knife.
Step #13 Arrange slices, cut sides down, in 1 layer on a baking sheet.
Step #14 Repeat with remaining logs, transferring slices to sheets.
Step #15 Bake, turning over once, until golden & crisp, 35 to 45 mins total.
Step #16 Cool biscotti on baking sheets on racks, about 15 mins.