In a medium bowl, combine flour, cocoa powder, baking soda, and salt. Whisk together then set these dry ingredients aside. 125 g all-purpose flour, 45 g natural unsweetened cocoa powder, 3/4 teaspoon baking soda, 1/4 teaspoon salt
In a large mixing bowl or the bowl of a stand mixer add the room temperature butter and granulated sugar and brown sugar. Use an electric beater or the stand mixer with a paddle attachment to beat the butter and sugar on medium high speed until light and creamy. 113 g unsalted butter, 100 g granulated sugar, 100 g soft brown sugar
Add in the egg and vanilla extract and beat on medium speed until combined. 1 large egg, 1 teaspoon pure vanilla extract
Tip the flour mixture into the wet ingredients and fold them together with a rubber spatula or wooden spoon until nearly combined. There should still be flour streaks remaining. Add in the white chips and continue mixing until combined. 170 g white chocolate chips
Cover the bowl of dough and chill it in the fridge for at least 1 hour.
Pre-heat the oven to 350°F/180°C and line a baking sheet with parchment paper.
Use a cookie scoop or spoon, to scoop around 1.5 tablespoons of dough for each cookie ball.
Space the balls of dough around 2 inches apart on the lined baking sheet.
Bake the cookies in the preheated oven for around 10 minutes until baked around the edges but the middles are still soft. The exact baking time will depend on your own oven.
You can press in a few extra chocolate chips into the tops of the cookies while they are still hot. Let the cookies cool on the baking tray for 5-10 minutes to firm up before removing and placing them on a wire rack to cool further. Enjoy a still slightly warm cookie with a cold glass of milk.