These biscotti have two types of chocolate worked in - uneven rocks of chopped bittersweet chocolate (made using our handy Chocolate Chipper Jen got us!) and Dutch-process cocoa powder. The bittersweet chocolate pieces are worked in the dry ingredients, along with the whole, unsalted pistachio nuts. You'll notice in the ingredient list that I used a combo of all-purpose and whole-wheat pastry flours, but you can use completely all-purpose if desired. I like throwing the pastry flour in all sorts of different recipes for extra nutrition as it is lighter than regular whole-wheat flour, leaving you with baked goods that retain the familiar texture one is used to. White whole-wheat flour is great for this too, but it is often more expensive and not as easy to find.
To bind that mixture together, eggs, a couple pats worth of melted butter, vanilla and the smooth cocoa powder are whisked together and poured in. Start out by using a sturdy wooden spoon to bring the dough together, but do note that this will be fairly stiff and on the drier side - I ended up just using my hands to lightly finish incorporating the last few bits. After halving the dough to get two even pieces, instead of using flour to ease rolling the dough into logs, they are formed on a bed riddled with crunchy granulated sugar. Just before going into the oven, the logs are sprinkled with a touch more sugar on top for sparkle.
The first trip through the oven, the logs are baked until they have risen and are firm in the center if you lightly press on the tops - a good point to check is when you smell an overwhelming burst of chocolate aroma streaming out from the oven. As we've been doing for some time now, after the biscotti loaves have had a chance to cool down, we spritzed the top with just a little water - this ever-so-slightly softens the outer crust, allowing you the slice through them with little crumbling. You may think that using the whole nuts would make them difficult to slice, but the nuts are pretty tender while the loaves are still warm and don't resist much - just use a serrated knife and it should glide through.
Baked for a second time to dry them out, giving the crunchy texture one wants with biscotti, you can shorten the second trip through the oven if you don't like them quite as hard - try shaving 5 to 7 minutes off and see how you like it. While the cocoa powder adds a more delicate chocolate flavor, bringing that bittersweet chocolate ensures you get a satisfying chocolate fix without making the biscotti too sweet. If you want to intensify the chocolate essence, try dispersing a couple teaspoons or so of instant espresso powder into the melted butter - it won't come across as a coffee flavor, but pairing it with chocolate heightens the subtle notes that tend to get masked. If you don't groove on pistachios, don't be shy in swapping them out - think about peanuts, almonds or even hazelnuts for a nutella-like tone.