Melt the Butter: Begin by melting 10 tablespoons of unsalted butter in a small pan over medium heat. Stir occasionally until the butter turns golden brown, about 5-7 minutes. Remove from heat and let cool slightly.

Combine the Sugars: In the same pan, add ⅔ cup of brown sugar and ¼ cup of white sugar. Stir gently over low heat for 1-2 minutes until dissolved. Cool for about 10 minutes.

Add Wet Ingredients: Whisk in 1 large egg, an additional egg yolk, 1 teaspoon of vanilla extract, and dissolved instant coffee until smooth and glossy.

Mix Dry Ingredients: In a separate bowl, sift together 1 cup of all-purpose flour, ⅓ cup of cocoa powder, ¾ teaspoon of salt, ½ teaspoon of baking soda, and ¼ teaspoon of baking powder. Whisk to combine.

Combine Wet and Dry Mixtures: Gradually fold the dry ingredients into the wet mixture using a spatula. Mix gently until just combined, being careful not to overmix.

Add Chocolate Chunks: Gently fold in 5 ounces of chopped chocolate, ensuring even distribution throughout the dough for a rich flavor.

Form the Dough Balls: Portion out the dough into balls about 2 tablespoons each on a parchment-lined baking sheet, spacing them apart.

Chill the Dough: Cover with plastic wrap and refrigerate overnight to develop flavors and achieve a fudgy texture.

Preheat the Oven: Preheat oven to 350°F (175°C) and prepare another baking sheet with parchment paper.

Bake the Cookies: Place chilled dough balls onto the baking sheet and bake for 10-12 minutes until edges are set and centers are slightly soft.

Cool and Serve: Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack. Enjoy!