Preheat the oven to 180°C/350°F. Line a large baking tray with greaseproof paper or a silicone mat.
Heat the butter in a saucepan or small frying pan over medium heat and whisk continuously until the butter begins to foam and darkens and smells nutty. Be very careful not to burn it! It changes very quickly - so it is worth only focusing on this one thing whilst doing it. Set aside to cool for a few minutes whilst you prepare the rest of the ingredients.
¾ cup unsalted butter
In a medium mixing bowl, combine the all-purpose (plain) flour, cornstarch (cornflour), baking powder, baking soda (bicarbonate of soda) and fine sea salt. Stir together using a whisk, to ensure all the ingredients are evenly distributed.
2 ½ cups all-purpose (plain) flour, 2 teaspoons cornstarch, 1 teaspoon baking powder, ½ teaspoon baking soda, ¼ teaspoon fine sea salt
In the bowl of a stand mixer, combine the brown sugars and granulated sugar with the slightly cooled (but still warm) brown butter. Mix on medium speed, just until well combined. (Alternatively use a large mixing bowl and an electric hand mixer).
¾ cup packed dark brown sugar, ¼ cup granulated sugar
Add the egg and vanilla to the butter and sugar mixture and continue to mix on medium speed until well combined.
1 medium egg, 1 ½ teaspoons vanilla extract
Add the flour mixture and mix on low speed until no streaks of flour remain.
Add the chocolate chips to the cookie dough. Mix on low speed until evenly distributed throughout the dough.
1 cup white chocolate buttons
Divide the dough in half, keeping one half of the dough to one side in a medium mixing bowl. To one half of the dough, add the molasses and the ground spices and extra flour, stir well until combined.
2 tablespoons molasses, 1 ½ teaspoons ground ginger, 1 teaspoon ground cinnamon, ¼ teaspoon ground nutmeg, ⅛ teaspoon ground cloves, 2 tablespoons all-purpose flour
Use a small cookie scoop to scoop the dough into approximately 1 tablespoon-sized balls of each half of the mixture. Press them together and swirl them slightly if you can. Roll into balls and place on the prepared baking tray. You should get 6-8 on a tray at a time.
Bake in the preheated oven for 8-10 minutes (mine are perfect after 9 minutes in a fan-assisted/convection oven) until lightly golden at the edges. They should still feel soft and underbaked in the centre – that’s what you want! They’ll continue to bake as they cool. Makes 16.