In a medium bowl, whisk together flour, baking powder, and salt. Whisk in the cinnamon.

In the bowl of a stand mixer fitted with the paddle attachment, cream butter on medium speed until smooth and shiny, about 1 minute. Slowly add sugar and continue to beat on medium until light and fluffy, about 5 minutes. Scrape down sides of bowl.

Add eggs, one at a time, beating thoroughly (about 1 minute) between additions, scraping down the bowl as needed.

Add flour in two additions, pulsing the mixer to start, then running on low just until the flour is incorporated, about 15 seconds.

Add walnuts and cranberries, pulsing to mix. Transfer dough to an airtight container and refrigerate overnight.

Preheat oven to 325°F. Line two baking sheets with parchment or silicone baking mats.

Divide dough into 4 pieces and roll each into a log about 1 inch in diameter (it's easiest to roll on a silicone baking mat).

Transfer to prepared baking sheets, leaving 3 inches of space between logs. Repeat with the remaining dough to make four logs total.

Bake 40 minutes, rotating from front to back and top to bottom halfway through, or until golden brown and dough is set.

Let cool 20 minutes.

Reduce oven heat to 300°F.

Slice each log diagonally into slices 1/2 inch thick. Place slices on baking sheets and return to oven.

Bake 15 minutes, flip each slice, then bake another 15 minutes, or until dried. Let cool completely before transferring to an airtight container.