In a large bowl, sift together the dry ingredients (flour, cocoa powder, baking soda, and salt).
In a bowl of a stand mixer, cream the butter with sugar until smooth and creamy. About 2 minutes.
Add egg and vanilla, and beat again for 1 minute.
Add the dry ingredients to the wet ingredients, and mix again until just combined. Then add the yogurt or buttermilk and mix again until just combine.
Fold in the chopped chocolate chunks, cover the bowl and chill the dough for 30 minutes.
Use a medium cookie scoop, scoop out dough balls and flatten into disks. Do this in batches to keep the dough chilled.
Wrap the cookie dough around each caramel, and chill again for 15 minutes.
Meanwhile preheat oven to 350°F/180°C, then place the chilled cookies on a cookie sheet lined with parchment paper or silpat about 2 inches apart.
Bake for 10-12 minutes rotating the pan halfway through.
Sprinkle the cookies with sea salt right after you remove them from the oven, then cool on the cookie sheet for 10 minutes. Transfer to a wire rack to cool completely.