Preheat the oven to 180°C/350°F. Line a large baking tray with greaseproof paper or a silicone mat.
Melt the butter in a small saucepan. 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), pumpkin spice and fine sea salt. Stir together using a whisk, to ensure all the ingredients are evenly distributed.
2 ¾ cups all-purpose (plain) flour, 1 tablespoon cornstarch, 1 teaspoon baking powder, 1 teaspoon baking soda, 1 ¾ teaspoons pumpkin spice, ½ 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) melted butter. Mix on medium speed, just until well combined. (Alternatively use a large mixing bowl and an electric hand mixer).
½ cup packed light brown sugar, ½ cup packed dark brown sugar, ¼ cup granulated sugar
Add the pumpkin puree, egg yolk and vanilla to the butter and sugar mixture and continue to mix on medium speed until well combined.
⅓ cup pumpkin puree, 1 egg yolk, 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 chocolate chips, plus a few extras for the tops, if desired
Use a medium cookie scoop to scoop and roll the dough into approximately 2 tablespoon-sized balls (you should get 22-24 cookies from this mixture) and place on the prepared baking tray. You should get 6-8 on a tray at a time. Add a few extra chocolate chips to the tops, if desired.
Bake in the preheated oven for 8-10 minutes (mine are perfect after 8 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 22-24 cookies.
Leave to cool on the tray for 5-10 minutes before transferring to a wire rack to cool completely (or for as long as you can bear to wait!) Enjoy!