Preheat the oven to 375° F. Line a large baking sheet with parchment paper or a Silpat mat.
Mix together the flour, baking soda, salt and baking powder in a large bowl. Hold this aside.
Cream together the softened butter, granulated sugar and brown sugar in the bowl of a stand mixer or in a large bowl with a hand mixer. Cream the butter and sugars for about 5 minutes. Mix in the eggs one at a time, then add the vanilla extract and mix this in, too. Beat in the peanut butter until the mixture is smooth.
Add the flour mixture to the bowl in two additions, scraping the bowl a couple of times to be sure everything is incorporated.
Make cookie dough balls with caramel:
Scoop out a portion of the dough using a 1½ tablespoon-sized cookie scoop.
Take an unwrapped caramel, squeeze a little into a ball shape, then push the caramel into the dough ball. Fold the dough around the caramel until just a tiny bit peeks out.
Place the caramel cookie dough balls on the baking sheet spaced about two inches apart.
Bake the cookies:
Bake the cookies for 13 minutes, until the edges are set. The cookies will be flattened with a pool of caramel in the center. Let the cookies cool on the baking sheet for 5 minutes, then move them to a cooling rack.
Sprinkle a little flake sea salt over the tops of the cookies.
Repeat the dough and caramel steps, and the baking until all the cookies are baked.
Store the cookies in a sealed container at room temperature for up to 4 days. Makes about 39 cookies.
Notes
Caramels: Don't skimp on the quality of the caramels. (I found out the hard way on this one.) You want the caramels to be soft after baking, and rock-hard, cheap caramel cubes will not be. Use a good brand of soft caramels.
Butter: Use unsalted butter in these cookies. (A good idea with baking in general.) That way the cookies don't turn out more salty than you're expecting.
Peanut butter: I use creamy peanut butter for these cookies. Want to experiment with crunchy peanut butter? Go for it! However, this recipe has not been tested with natural peanut butter, which is more oily, so stick with regular peanut butter.
Equipment: A stand mixer or hand-held mixer, a couple of large bowls, baking sheets, parchment paper, a spatula, and a cooling rack.
Shaping the caramels: The Werther's Soft Caramels are cylindrical in shape but they're also—soft! Just squeeze the caramels between your fingers and you'll get a squat shape that you can easily tuck in the cookie dough.
Freezing: Because of the caramel centers, I don't recommend freezing the baked cookies. However, the peanut butter cookie dough alone will freeze very well. Seal it well in a freezer-proof bag, and store in the freezer for up to three months. Allow it to thaw in the fridge, then follow the recipe to scoop it and add the caramels.