Preheat the oven to 350 degrees F (180 degrees C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the All-Purpose Flour (1 3/4 cup), All-Purpose Flour (2 tablespoon), Unsweetened Cocoa Powder (1/4 cup), Unsweetened Cocoa Powder (2 tablespoon), Baking Soda (1 teaspoon) and Salt (3/4 teaspoon).
In the bowl of an electric mixer, cream the Butter (1 stick). Granulated Sugar (3/4 cup) and an additional 2 tablespoons of sugar until light and fluffy, 1 to 2 minutes. Scrape down the sides of the bowl with a rubber spatula.
Add the Large Egg (2), one at a time, scraping down the bowl and mixing well after each addition. Beat in the Vanilla Extract (2 teaspoon).
Add the dry ingredients and Semi-Sweet Chocolate Chips (1 cup) and stir on low speed until just combined.
Dust a work surface with flour. Using a rubber spatula, scrape the sticky dough out onto the work surface and dust the top of the dough lightly with flour. Using your hands, shape the dough into a rough ball (if it's still too sticky, dust with a bit more flour) and cut in half.
Form the dough pieces into two short logs by rolling back and forth.
Place the logs onto the prepared baking sheet and shape into longer logs about 3/4 inch high and 2 inches wide. Allow enough space for the logs to spread a few inches while they bake.
Bake for about 35 minutes, until firm to the touch.
Let the biscotti logs cool on the pan for about 5 minutes, or until just cool enough to touch (if you wait any longer, the biscotti will be difficult to cut); then, using a sharp knife, slice the logs on the diagonal into 3/4-inch slices (I do this right on the baking sheet).
Turn the biscotti on their sides (so that the cut sides are down) and place back in the oven for 10 minutes to dry and crisp up.
Let cool on the pan for a few minutes, then transfer to a wire rack to cool completely.
When cool, push all the biscotti together. This prevents the Powdered Confectioners Sugar (1 tablespoon) from getting on the sides of the cookies. Use a fine sieve to dust with Confectioners sugar. Serve with coffee, tea or warm milk, and enjoy!