Zest 1 navel orange into a bowl. In another bowl, juice the orange. Weigh or measure the flour, baking powder, salt, ground cinnamon and whisk to blend. To help keep the cookie dough's roundness in the refrigerator, I have taken a paper towel cardboard center and cut it in half. Then put the 2 halves together, and you will lay the log onto the paper towel cardboard by overlapping the halves.
In a stand or hand-held mixer, beat the butter on medium speed till it is creamy and light in color, about 3 minutes. Turn your mixer down to a low setting and gradually add the powdered sugar. Once incorporated, turn the speed back to medium and mix for about 2 minutes. I like to scrape down the side and blend for about 30 more seconds. Add the vanilla extract, orange juice, orange zest, and mix through the cookie dough. Turn the mixer to low and slowly add the flour mixture till incorporated. I turn off the mixer and scrape down the sides and blend for another 30 seconds across the bottom. Turn the mixer off, add the mini chocolate chips, chopped walnuts, and diced orange peel and mix it for about 30 seconds.
Take the bowl off the stand and scrape the cookie dough onto a non-stick pastry mat. You can flour it but not too much. The cookie dough will be a little tacky. You have a choice of rolling one large roll or divide the cookie dough in half and make 2 smaller rolls. I have a half sheet cookie pan, so I make one large roll and fit the roll diagonally on the pan. If you do not have a large pan that will fit into the refrigerator, make 2 small rolls. You can hand mix the dough to ensure the chocolate chips, walnuts, and orange peel are distributed evenly throughout the cookie dough before you start to roll the dough. Roll the cookie dough into a log shape.
Taking a plastic wrap piece that is longer than the width (you want to fold the wrap on the ends) and places it right next to the rolled cookie dough. All you need to do is roll it onto the plastic wrap and roll then fold over the ends. Lay the log onto the paper towel pieces. The paper towel cardboard helps to keep the log shape and will give you rounder cookies. Place the pan with the log into the refrigerator for about an hour. This will make the slicing of the log easier if the cookie dough is firm.
Preheat the oven to 350° and line a cookie pan with parchment paper. Taking the cookie log out of the refrigerator and unwrap. Placing the log onto a cutting board and cut each cookie about ⅜" to ½" thick. I put 12 slices on a cookie sheet and baked for 11-13 minutes. You want the cookies to be a little golden around the bottom edges. Leave then on the cookie pan for 1 to 2 minutes before moving to a cooling rack. You want them to set a little before moving them. Makes about 2-½ dozen.