Step 1: Start by making the cookie dough. In a stand mixer, beat together the butter, sugar, and vanilla until smooth. Add the flour and salt, and beat until everything is mixed well. Stir in the chocolate chips.

Step 2: Line an 8"x8" baking dish with parchment paper, allowing some to hang over the sides. Spread half of the cookie dough onto the parchment paper, pressing it down to create a thin, even layer. Cover it with another piece of parchment paper and repeat with the remaining cookie dough. Put the dish in the freezer until the dough firms up, which should take about 2 hours.

Step 3: Once the dough is firm, take the pan out of the freezer and separate the layers. Cut them into eight large squares.

Step 4: Toast the marshmallows over a flame on the stove or under the broiler in the oven.

Step 5: Now, assemble your treats! Place chocolate and marshmallows between two squares of cookie dough to make delicious sandwiches. Enjoy!