Step 1: Preheat your oven to 375°F (190°C). Line two baking sheets with parchment paper.
Step 2: In a large bowl, cream together the softened unsalted butter, granulated sugar, and brown sugar with an electric mixer until light and fluffy.
Step 3: Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.
Step 4: In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.
Step 6: Add the blue gel food coloring to the dough and mix until a uniform, vibrant blue color is achieved throughout the dough.
Step 7: Gently fold in the semi-sweet chocolate chips (and white chocolate chips, if using) until evenly distributed.
Step 8: Drop rounded tablespoons of cookie dough onto the prepared baking sheets, spacing them about 2 inches apart. Optionally, lightly press a few extra chocolate chips on top of each cookie for a bakery-style look.
Step 9: Bake for 10-12 minutes, or until the edges are lightly golden and the centers are still soft. Do not overbake.
Step 10: Remove cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.