Using a hand or stand mixer, cream butter until light and fluffy. Add sugar, eggs, vanilla, and orange zest; mix until well combined. Add flour, baking powder, and salt, and mix until smooth. Add pistachios and cranberries and mix briefly to combine. Divide the dough in half (I weighed mine, of course), and pat each half into a log about 12 inches long and 1 inch tall. Place on a baking sheet and bake 35 minutes at 350F, until cookie logs are lightly browned.
Cool for 5 minutes, then remove to a cutting board. Carefully use a serrated knife to slice each log on the diagonal into 12 1-inch pieces. Place cookies on a cookie sheet cut side down and bake for 5 minutes. Flip the cookies, then bake another 5 minutes. Cool completely, then store in an airtight container.