In a bowl, mix together the flour, cocoa powder, baking powder, baking soda, salt and espresso powder and set aside
In a stand mixer, beat together the butter and sugars on medium speed until light and fluffy, 3 minutes, scraping down the sides of the bowl as needed.
Add the eggs and vanilla and beat to combine, about 60 seconds.
Add the dry ingredients, and mix until no flour streaks remain.
Mix in the 1 ½ cups chocolate and the caramels. Scoop and roll dough into 2 ½ inch (3 ounce) balls. Cover and chill dough for 30 minutes.
Preheat the oven to 350 degrees. Line 2 sheet trays with parchment paper.
Place the prepped cookie dough balls on the prepared sheet trays, spacing at least 2 inches apart. Top each ball with a piece of the remaining chocolate, pressing down slightly. Then sprinkle with flake salt.
Bake cookies for 12 minutes, then lightly bang on the counter to deflate slightly. Return to the oven and continue to bake until cookies are set and chocolate is very melty, 2-3 minutes longer.