Start by browning the butter. Place the butter in a saucepan over medium heat and gently stir. Butter will melt and foam up. It gradually changes colour from a light amber colour to a darker honey colour. Keep an eye on it, as it burns very quickly. The fat content of the butter starts to solidify and show like brown specks at the bottom of the pan. That is when you should remove the butter from the heat and pour it into a large bowl.
¾ cup Butter
Immediately add both sugars and whisk until the sugar is dissolved.
½ cup Dark brown sugar, ⅓ cup Granulated sugar
Mix well in the egg, egg yolk, and vanilla extract.
1 Egg, 1 Egg yolk, 1 tablespoon Vanilla extract
Next, add the red food colouring and white vinegar and mix well.
½ tablespoon White vinegar, ½ tablespoon Red food coloring
Sift the all-purpose flour, cocoa powder, salt, baking powder and soda in a separate bowl. Add the dry ingredients to the butter mixture and gently mix.
1¼ cup All-purpose flour, 1 tablespoon Cocoa powder, 1 teaspoon Espresso powder, ½ teaspoon Baking powder, ¼ teaspoon Baking soda, ½ teaspoon Salt
At the end, add the chopped chocolates and mix. Scoop the dough onto a baking sheet. Place a few pieces of chopped chocolate on each cookie and chill them for at least one hour.
⅓ cup White chocolate, ½ cup Dark chocolate, ½ cup Milk chocolate
Preheat the oven to 350F. Place the chilled cookie dough balls on the lined cookie sheet and leave a two-inch gap between them.
Bake them for 10-12 minutes or until their edges look set. Remove them from the oven and immediately go around them with a large round cookie cutter to make their edges round. Let them cool on the baking sheet for 10 minutes, and then transfer them to a cooling rack to cool down fully.