Preheat oven to 375 degrees.
In a bowl, combine flour, cornmeal, baking soda, salt and rosemary. In mixer, cream together butter and sugar until light yellow. To mixer, add mustard, Parmesan cheese and eggs. Mix to combine, about 2-3 minutes on low. Add dry ingredients slowly. Combine until dough forms a ball.
Transfer dough to a lightly floured board. With lightly floured hands, bring dough together into disc. Cut in half. With each half, roll into a 12 inch log (you may need a small amount of flour to prevent sticking). Transfer each log to Silpat or parchment lined baking sheet. Flatten each log until 2 inches wide. Lightly score individual biscotti, about 12 cookies to each log.
Place baking sheet on the middle rack of oven and bake for 20 minutes. Allow to cool for 5-10 minutes. Cut individual biscotti and return biscotti to baking sheet, standing upright. Bake another 10 minutes until they are golden and crisp. Allow to cool completely. Store in air-tight container.