How to Make It
Center a rack in the oven and preheat to 350°F. Line a baking sheet with parchment paper or a silicone baking mat.
Whisk the flour, baking powder, cinnamon (if you’re using it), and baking soda together.
Working in a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter, sugar, salt, and citrus zest (if you’re using it) on medium speed until smooth and creamy, about 2 minutes. Scrape down the sides and bottom of the bowl. Add the eggs one at a time, beating for 1 minute after each one goes in. (Don’t be discouraged if the mixture curdles at this point.) Beat in the oats and scrape the bowl again. With the mixer off, add the dry ingredients all at once. Pulse the mixer a couple of times and then beat on low speed until the flour is almost incorporated. Scrape down the bowl, add the granola, almonds and cranberries and mix on low only until blended into the dough.
Turn the dough out and divide it in half. Use your fingers and a spatula to shape each piece of dough into a rectangle that’s 10 to 12 inches long and about 1 ½ inches wide. The logs will be ragged and rough, but that’s fine. Put each log a few inches away from one of the long sides of the baking sheet—leave room between them because they’ll expand in the oven.
Bake the logs for about 25 minutes, rotating the baking sheet after about 15 minutes; the logs should be cracked and lightly browned but still squeezable. Transfer the baking sheet to a rack and let the logs rest for 20 to 30 minutes.
If you have turned off your oven, bring it back to 350°F.
Using a wide metal spatula, transfer the logs to a cutting board and, with a long serrated knife, cut into ½-inch-thick slices. Return the slices to the baking sheet—placing them cut side down in rows—and slide the sheet back into the oven. Bake the biscotti for another 15 minutes. Pull the sheet from the oven, flip over the biscotti, and bake for about 10 minutes more, until they are a golden brown and almost firm to the touch—they’ll get harder as they cool. Transfer them to racks to cool completely.
These will keep for at least five days at room temperature in a covered container. You can even leave them out in a basket—if they get a little hard, just dip them a little longer in whatever you’re sipping along with them.