Start by toasting the oats in a pan on a medium-low heat. Once the oats smell like popcorn and are a deep golden brown, transfer aside to cool. This will take around 5-7 minutes
To make brown butter, melt the butter in a pan on a low heat until completely melted. Then turn the heat to medium. The butter will foam up and then subside, and white/cream specs will form at the bottom
Once these specs (milk solids) have turned a deep brown, transfer the brown butter to a cool pan or bowl to prevent further cooking and burning. Allow to cool
Once the brown butter has cooled, transfer to a large mixing bowl and add in the white sugar, brown sugar and vanilla. Whisk just until incorporated. The mixture will start off runny and very quickly thicken up. Avoid over whisking
Add the flour, salt, baking powder, toasted oats, nuts and most of the dark chocolate to the butter and sugar. Keep a small handful of chocolate aside for pressing into the cookies
Start mixing for around 1 minute, then add in the milk and mix until all incorporated
Weigh 60g of cookie dough for each cookie and roll into a ball. Place on a lined baking tray, spaced out with 2” between each cookie dough ball
Press a few extra pieces of chocolate into the top of the cookie dough ball, then bake in a preheated oven at 150’C fan/170’C conventional for 15-16 minutes. The outer edges of the cookies should be just slightly firm to the touch
As soon as the cookies are out of the oven, use a round cookie cutter that’s larger than the cookies to rotate around them. This will help to shape them into an even round shape.
Allow to cool on the tray for 5 minutes to firm up, then transfer to a wire rack to cool completely
Finish with flaky sea salt for added flavour (optional)