Begin by preheating your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking and facilitate easy clean-up.
In a large mixing bowl, combine the softened unsalted butter, brown sugar, and granulated sugar. Use an electric mixer on medium speed to cream these ingredients together until the mixture is light, fluffy, and pale in color—about 3-5 minutes.
Incorporate the eggs into the creamed mixture, adding them one at a time and mixing well after each addition to ensure a homogeneous batter. Stir in the vanilla extract until fully integrated.
In a separate bowl, whisk together the all-purpose flour, baking soda, fine sea salt, and instant espresso powder. This step combines the dry ingredients, eliminating clumps and ensuring even distribution.
Gradually introduce the dry ingredient mixture to the wet mixture, mixing on low speed just until combined. Be cautious not to overmix; a few streaks of flour are okay!
Gently fold in the semi-sweet chocolate chips and dark chocolate chunks with a spatula, ensuring they are evenly distributed throughout the dough for a delightful chocolate experience in every bite.
Using a tablespoon or cookie scoop, portion out balls of dough and place them on the prepared baking sheet, making sure to space them about 2 inches apart for proper spreading.
For an enhanced flavor experience, sprinkle a small pinch of flaky sea salt atop each dough ball before baking. This step elevates the sweetness and amplifies the chocolate flavor!
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden and the centers appear slightly soft, as cookies will continue to cook on the sheet after removal.
Once they’re done, take the cookies out and allow them to cool on the baking sheet for about 5 minutes. This resting period helps improve their texture before transferring them to a wire rack to cool completely.
Notes
For an elegant touch, sprinkle more flaky sea salt on top before serving.