In a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter with the sugar and light brown sugar for 2 minutes. It should be light, fluffy, and have turned a slightly paler color.
½ cup unsalted butter, ½ cup white sugar, ½ cup light brown sugar
Stop the mixer and use a rubber spatula to scrape the sides and bottom of the bowl. Add the egg and vanilla extract, then beat again on medium speed for 1 minute until combined.
1 large egg, 1 teaspoon vanilla extract
Stop the mixer and add all of your dry ingredients - flour, baking powder, baking soda, salt, espresso powder (if using), and cocoa powder. Beat on low speed so the dry ingredients don't go flying out! Make sure to stop the mixer and scrape the sides and bottom of the bowl again so everything gets mixed together.
1 teaspoon kosher salt, 1 ¼ cups all purpose flour, ½ teaspoon baking powder, 1 teaspoon baking soda, ⅓ cup dutch processed cocoa powder, 1 teaspoon fine espresso powder
Stir in the chopped chocolate, but leave some of the chopped chocolate to the side to top the cookie dough balls later.
⅓ cup white chocolate bar, ⅓ cup dark chocolate bar, ⅓ cup milk chocolate bar
At this point, you can either bake right away if you prefer a thinner cookie or chill the cookie dough. If chilling the cookie dough (which I recommend), you can either place the whole bowl in the fridge or scoop out the cookie dough already. It is a sticky dough, so keep that in mind! If scooping already, just scoop out 3 tablespoons of cookie dough using a large cookie scoop and place on a parchment-lined baking sheet. Chill in the fridge for 2-3 hours.
Preheat the oven to 350°Fahrenheit/175°Celsius and line 2 baking sheets with parchment paper.
If you haven't done so yet, scoop out 3 heaping tablespoons of cookie dough and place them on the prepared baking sheets, making sure there is space between each cookie dough ball.
Use your hands to turn the cookie dough balls into columns, so they're tall instead of being round pieces of dough. Place the extra chopped chocolate on top of these stacks.
Bake the cookies one sheet at a time for 9-12 minutes. While one sheet is baking, I place the other sheet in the fridge.
Once out of the oven, scoot the cookies using a mug or biscuit cutter to get that perfect round shape. You can also add more chocolate chunks on top and a sprinkle of flaky sea salt!
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. I'm using Diamond Crystal Kosher Salt and not Morton Kosher Salt, which is too salty for this recipe!Chilling: I tested these cookies by chilling and not chilling the cookie dough. If you chill them, you will have a thicker cookie.Chocolate: To make these cookies extra chocolatey, gently press on extra chocolate as soon as they come out of the oven.Types of Chocolate: If you don't love milk chocolate or white chocolate, just add in an equal amount of another chocolate bar. Storage: keep the baked cookies in a tupperware for up to 5 days at room temperature. Freeze unbaked cookie dough balls for up to 2 months. When ready to bake, take them out of the freezer and bake at the same temperature as above but for an extra minute or two.