Preheat oven to 350°F (175°C).
Use a Doughmakers Baking Sheet or line a baking sheet with parchment paper. Using a stand mixer with a paddle attachment or a hand mixer, cream butter, shortening, granulated sugar and brown sugar until light and fluffy.
Beat in eggs, one at a time, ensuring each is fully incorporated before adding the next. Pour in pure vanilla extract.
In a separate bowl, whisk together flour, baking soda and salt. Slowly add the dry ingredients beating just until combined.
Divide the dough into four equal parts. Add a few drops of different food coloring (purple, blue, pink, yellow) to each part. Mix until the color is incorporated.
Take small pieces of each dough and gently roll them together. This will create the marbled look.
Place the dough balls onto the prepared baking sheet. Press in chocolate chips.
Bake for 10-12 minutes or until the edges are set and slightly golden but the centers remain soft.
Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
Serve and enjoy!
Store cookies in an airtight container for up to 5 days. For longer storage, free cookies in an airtight container, placing wax paper between layers, for up to 3 months. Thaw them at room temperature before serving.