Combine the flour, salt, pepper and the chopped rosemary in a food processor. Add the butter and pulse until the mixture resembles a course meal. Add the Parmesan cheese and pulse to mix. Add 1 tablespoon of the sour cream at a time, pulsing each time. Add the milk and pulse until the dough comes together. It’s important not to run the food processor too much or the dough becomes tough.
Place the dough in a piping bag with a star tip. Pipe the dough into long strips on a sheet tray line with wax paper and place in the refrigerator to chill. After a couple hours remove the dough from the refrigerator and place on a cutting board. Cut 2 inch long portions and return to the sheet tray with wax paper. Refrigerate until it is time to bake.
Preheat the oven to 325 º F. Line a sheet pan with parchment paper and place the cheese straws on the sheet tray. Bake in a 325º F oven until the crackers are golden brown and firm in the center, approximately 25 to 35 minutes.
Place on a platter or in a basket and serve. Take a look at the recommended pairing below.