Preheat your oven to 375 degrees Fahrenheit and line a baking sheet with parchment paper. Set it aside for later use.

In a medium-sized mixing bowl, combine the flour, cocoa powder, baking powder, salt, and baking soda. Whisk these dry ingredients together thoroughly, and then set the bowl aside.

Using a stand mixer fitted with the paddle attachment, beat the softened butter and sugars together on medium speed until they achieve a light and fluffy texture, typically around 2 minutes.

Add the whole egg, egg yolk, and vanilla extract to the mixture, continuing to mix until they are fully combined. Scrape down the sides of the bowl.

Reduce the mixer speed to low and gradually add the dry ingredients in three separate additions. Mix until the dry ingredients are fully integrated into the dough, being careful not to overmix.

Now, gently fold in the white chocolate chips and milk chocolate chips until they are evenly distributed throughout the dough.

Using a kitchen scale, measure out 5 ounces of cookie dough and shape it into balls. Place these dough balls onto the prepared baking sheet, ensuring they are spaced apart. Top each cookie dough ball with additional white and milk chocolate chips. You can even roll the cookie dough balls to evenly coat them in chocolate chips while they bake. Carefully press down the cookie dough balls slightly.

Bake the cookies in the preheated oven for approximately 11 minutes, or until they appear set around the edges but slightly soft in the center.

Once baked, allow the cookies to cool on the baking sheet for about 10 minutes before serving. If you plan to enjoy them later, simply reheat a cookie in the microwave for approximately 15-20 seconds to savor its warm, gooey goodness.