Place the butter in a small saucepan and cook over medium heat, swirling the pan occasionally. The butter will froth up and you will see brown particles forming along the top of the butter. Stir the butter occasionally and when the butter turns into a dark amber color, remove from the heat. Set aside to cool in the fridge and continue with the rest of the recipe.
Chop the chocolate bars into small 1/4-inch size pieces. On a large piece of parchment paper, whisk together the flour, baking powder, baking soda and salt.
Place the cooled brown butter into the bowl of the stand mixer. There will be browned bits at the bottom of the pan and add these as well as they will intensify the flavor.
Add the brown sugar to the butter and mix on medium high speed until light and creamy. Add the egg and yolk and continue beating until well incorporated. Tip in the dry ingredients and mix until just combined. On low speed, add in the caramel Chipits and chopped chocolate.
Scoop rounded balls of dough onto the prepared cookie sheets, 2 inches apart. Refrigerate for 30 minutes.
Preheat the oven to 360°F. Bake the cookies for approximately 15 minutes or until set and golden brown around the edges. Sprinkle the warm cookies with sea salt. Let cool on the trays.
Note: These cookies will keep in an airtight container for one week in the refrigerator or cupboard and can be frozen for up to 2 months.