Begin by preheating your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking.
In a large mixing bowl, combine the unsalted butter and vegetable shortening. Using an electric mixer, cream them together until the mixture is light and fluffy.
Gradually add the granulated sugar to the creamed mixture, mixing until combined. Then, add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually add this mixture to the wet ingredients, mixing until just combined.
Gently fold in the semisweet chocolate chips, ensuring they are evenly distributed throughout the dough.
Divide the dough in half and shape each half into a log about 12 inches long and 2 inches wide on the prepared baking sheet. Leave space between the logs as they will expand during baking.
Bake in the preheated oven for 25-30 minutes, or until the logs are lightly golden and firm to the touch.
Remove from the oven and let the logs cool on the baking sheet for about 10 minutes. Transfer them to a cooling rack to cool slightly. Once cool enough to handle, slice each log diagonally into ½-inch thick pieces.
Arrange the slices cut-side up back on the baking sheet. Bake for an additional 10-15 minutes, turning them halfway through for even crispiness.
Allow the biscotti to cool completely on the baking sheet before serving or storing.
