Prep: Preheat oven to 350°F. Line a baking sheet with parchment paper and set aside.
Roll out dough: On a floured surface, roll out one disc of cookie dough until it's about ⅛" thick.
Cut out top cookies: Use a 3" scalloped round cookie cutter to cut out rounds from the dough. Slide an offset spatula under each round to lift it off the counter if it's sticking. Transfer the rounds to your lined baking sheet. These cookies don't spread much so you can place them close together. Re-roll the scraps and repeat.
Cut out window: Use a smaller 1" scalloped cookie cutter to cut out the middle of each round. You can bake these tiny cutouts for a snack or add them to your scrap dough to re-roll.
Bake top cookies: Bake the cookies with the cutouts (the "top" cookies) for about 9 minutes or until the surface looks dry and set. Let them cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
Cut out bottom cookies: Repeat rolling out the second disc of dough in the same way as the first disc and use the same 3" scalloped round cookie cutter to cut out rounds from the dough. Transfer the rounds to your lined baking sheet. Do not cut out the middle of these cookies.
Bake bottom cookies: Bake these cookies (the "bottom" cookies) for about 10 minutes or until the surface looks dry and set. Let them cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
Dust with cocoa powder: Lay all the top cookies out on a wire rack or a sheet of parchment paper. Use a fine mesh sieve to dust the tops with cocoa powder or powdered sugar.
Sandwich caramel: If your salted caramel has hardened during this time, warm it in the microwave for about 15 seconds until it's soft and pliable. Transfer the caramel to a piping bag and snip the tip off (or use a spoon). Pipe a dollop of caramel in the middle of each bottom cookie. Place a matching top cookie on top to sandwich the caramel.