Preheat oven to 350 degrees F. In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Beat in brown sugar, salt, and, if desired, pumpkin pie spice, scraping the bowl occasionally. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour with a spatula or wooden spoon. Use your hands to bring dough together in a ball.
Pat or roll dough into a 12x8-inch rectangle (about 1/4 inch thick) on an ungreased baking sheet. Cut the 8 inch side of the dough into eight 1-inch strips (do not separate strips). Cut each strip lengthwise into six 2-inch sections (do not separate rectangles). After cutting, there should be 24 rectangles measuring 1x2-inches. Bake for 15 minutes. Remove from oven and cut the rectangles in half to make 48 smaller cookies. Bake for an additional 10 minutes or until cookies are lightly browned and crisp. Cool on cookie sheet on a wire rack.
In a small microwave-safe bowl, combine Ghirardelli(R) 60% Cacao Bittersweet Chocolate Baking Chips and shortening. Microwave on medium power (50 percent) for 1 minute. Remove and stir. If chocolate is not melted, return to microwave and repeat heating step, stirring every 30 seconds to avoid scorching. Stir until smooth. Dip cookies in melted chocolate; let excess drip back into the bowl. Placed dipped cookies on waxed paper; let stand until set. Enjoy immediately, store in an airtight container at room temperature for up to 3 days, or freeze up to 3 months.