Preheat oven to 350°F (180°C).
Using an electric mixer, beat the butter and pepper together. Add the flour and Jarlsberg at low speed, along with the walnuts, rosemary and bacon.
On a large sheet of parchment paper or plastic wrap, shape the dough into a long sausage shape about 1½-2 inches in diameter, and about six inches long. Refrigerate for at least an hour.
Line 2 large baking trays with parchment paper. Cut the dough into slices about ¼ inch thick. Place on trays and bake for 13-15 minutes, or until lightly golden around the edges.
Serve warm. Once cooled, they can be kept in a tightly sealed container for up to a week.