Add the brown and white sugar to the melted butter.
Whisk the butter and sugars until the mixture is emulsified - approximately 3 minutes of whisking.
Add the vanilla and eggs and whisk until smooth and creamy.
Add the dry ingredients and mix until just combined.
Add the chocolate chunks and salted caramel pieces then continue stirring, making sure to scrape down the bottom and sides of the bowl to prevent any dry pockets.
Scoop the dough onto a baking sheet lined with parchment paper (I use an ice cream/cookie scoop of around 2in/6cm). Cover with plastic wrap and refrigerate for 24-36 hours.
Preheat the oven to 400℉/200℃ and line two large cookie sheets with parchment paper.
Place the cookie dough balls on the prepared sheets, spacing them apart as the dough will spread slightly.
Bake the cookies for 8-10 minutes until they are a deep golden brown with the centers still soft – they will firm up as they cool. Sprinkle with flaky sea salt as they come out of the oven. Allow to cool for 5 minutes on the baking sheet then transfer to a wire rack.