Sift all dry ingredients and set them aside.
1¾ cup All-purpose flour, ½ teaspoon Baking soda, ½ teaspoon Salt, 1½ tablespoon Espresso powder, 1 cup Cocoa powder
First, brown the butter and let it cool. Browning butter takes about five to seven minutes. Place the butter in a light-coloured saucepan and heat it on medium heat until it starts to boil and from up. At this stage, butter is losing its water content. The fat contact starts to solidify. Keep stringing the butter until the fat contents are brown and brown. Keep stirring the butter until a coat of golden brown fat sits at the pan's bottom. Remove the pan from the heat, scrape the brown specks from the pan, pour the butter into the bowl of the stand mixer, and let it cool down. See the above pictures.
¾ cup Butter
Whisk the cool brown butter with both sugars until well blended using the whisk attachment.
1 cup Dark brown sugar, ⅓ cup Granulated sugar
Add in the egg and yolk with vanilla extract. Mix well.
1 Egg, 1 Yolk, 1 tablespoon Vanilla extract
Add them to the butter mixture. Add in the chocolate chips if using. Use an ice cream scoop to scoop the dough into small balls the size of a large walnut in the shell.
¾ cup Chocolate chips
Place them on a baking sheet and chill for an hour. Preheat the oven to 350F. Line the baking sheet with a baking mat or parchment paper. Place the chilled cookie dough balls on the baking sheets, leaving at least two inches of space between them. Place a few pieces of chopped chocolate on each cookie ball. Bake them for 8-10 minutes. Let them cool down on the tray for 10 minutes, then transfer them to the cooling rack.
½ cups Semi-sweet chocolate