In a medium-sized mixing bowl, add dry ingredients (flour, cornstarch and salt). Mix together with a rubber spatula. Set aside.Add sugar and butter to a large mixing bowl and cream together using an electric hand mixer. Add extracts and mix together thoroughly.Add orange zest and half of the flour mixture. Mix with a rubber spatula, being careful to not over-mix. Add remaining flour and combine with the spatula.Divide cookie dough in half and, using your hands, combine dough into a log-like shape. Place onto a piece of plastic wrap and seal. Roll on your counter to create a log shape.Using a ruler to measure, roll the dough until it’s about 7 inches long. If necessary, squash the ends in and roll out again until you get the desired size and dough no longer looks dry.Refrigerate dough for at least 30 minutes (up to overnight).Heat oven to 350ºF.Slice cookie dough to about ¼ inch thick and place on a parchment-paper-lined cookie sheet. Bake for 9–10 minutes. Place cookies on a cooling rack.While cookie dough is baking, place chocolate and white chocolate chips into separate microwavable bowls. Heat in the microwave for 1 minute in 15-second intervals (or until melted). After 45 seconds, mix chocolate using a spoon. (Optional: drop a little drop of vegetable oil into both bowls, it will make it easier to mix the melted chocolate.) Place into two separate piping bags or zippered plastic bags and cut the tip or corner. Pipe over cooled shortbread cookies.Place in the refrigerator for a few minutes to harden the chocolate.