01 -
Slice the marshmallows in half and place in the freezer while you prepare the dough.
02 -
Preheat the oven to 375°F. Line two baking sheets with parchment paper and set aside.
03 -
In a stand mixer with the paddle attachment, or using a hand mixer, mix cold butter, granulated sugar, and brown sugar on low speed. Gradually increase speed and cream for 4 minutes until pale and fluffy. Scrape down the sides of the bowl.
04 -
Add the egg, followed by the egg yolk, one at a time, mixing after each addition and scraping down the sides. Mix in vanilla extract.
05 -
In a separate bowl, whisk together flour, baking soda, corn starch, and salt.
06 -
Add the dry mixture to the wet ingredients in two additions. Mix on low speed until just combined. Avoid overmixing.
07 -
Add the graham cracker crumbs and chocolate chips to the dough, folding gently with a large spatula. Do not overmix.
08 -
Divide the dough into 2-ounce balls using a large cookie scoop. Place on a parchment-lined baking sheet, spacing 2 to 3 inches apart.
09 -
Press a well in the center of each dough ball and place half a marshmallow into it. Add 2 to 3 caramel pieces around the marshmallow. Shape dough around the filling, sealing it completely. Roll between palms to smooth.
10 -
Bake on the center rack of the oven for 9-10 minutes, until edges are set and golden, and centers are puffy but slightly underbaked.
11 -
Allow cookies to cool on the baking sheet for 5-10 minutes before transferring to a cooling rack.