Preheat the oven to 160C. Line 2-3 large baking trays with baking parchment. Place the butter and both sugars in a bowl of an electric mixer and beat on medium speed for about 6 minutes until sandy in texture. Add the egg, egg yolk and vanilla. Increase the speed to high and beat for 2 more minutes until pale and creamy. Place the baking powder and baking soda in a small bowl and mix with water. Add the baking powder mixture, flour, salt, cocoa, milk and chocolate to the butter mixture and beat on low speed until just combined.
Working in batches, scoop out about 2 tbsp of dough, roll into balls and place on the trays, leaving some space between as the cookies will spread. Bake for 10-13 minutes until or until golden brown and firm to the touch. Allow to cool on trays for 10 minutes, then move to the cooling rack to cool completely. Spread the cookies with caramel and sprinkle with sea salt. Enjoy!
Cookies can be stored in airtight container for up to 4 days (without the caramel and salt)
Baking times may vary, depending on the oven and size of your cookies.
Original recipe was calling for 60g of dough per cookie to be baked for 18-20 minutes. I've used 2 tbsp of dough per cookie, reducing baking time to 10-13 minutes.