Brush the bottom and sides of a 9-inch square baking pan with vegetable oil. Then, dust the pan generously with some powdered sugar by putting it through a fine mesh sieve. Knock out any excess sugar.
Vegetable oil for pan, 1 cup powdered sugar
In the bowl of a stand mixer, fitted with whisk attachment, add ½ cup water. Sprinkle gelatin over the top of the water and stir to make sure it all comes in contact with water. Set aside to soften.
½ cup water, 3 (¼ oz.) envelopes powdered unflavored gelatin
In a heavy 3- or 4-quart saucepan over medium heat, combine granulated sugar, corn syrup, and salt. Bring mixture to a boil, stirring until sugar is dissolved. Continue to boil without stirring until a candy thermometer reaches 240 degrees (soft ball stage). If the mixture bubbles up, turn down the heat a bit.
1 ½ cups granulated sugar, 1 cup light corn syrup, ¼ tsp salt
Remove saucepan from heat and let stand briefly until bubbles begin to dissipate.
While mixer is on low speed, pour hot sugar syrup into the softened gelatin by drizzling it in a thin stream down the side of the bowl.
Gradually increase mixer speed to high and beat until marshmallow gets thick and forms a thick ribbon when whisk is lifted, about 5 minutes.
Beat in the mint and vanilla extracts. Beat in a few drops of green food coloring, if desired.
1 teaspoon peppermint extract, 1 teaspoon pure vanilla extract, Green food coloring
Working quickly to prevent hardening, scrape marshmallow into the prepared pan (it will be very sticky) and use wet fingertips to make sure it's even and smooth on top.
Let baking pan stand at room temperature and uncovered for at least 4 hours, but ideally overnight. The surface should no longer be sticky and you should be able to gently pull marshmallow away from the sides of the pan with your fingertips.
Dust a cutting board with powdered sugar and use a rubber spatula to pull the sides of the marshmallow from the edge of the pan. This may take a bit of work and you may need to also use the spatula to loosen the marshmallow from the bottom of the pan. Invert marshmallow onto cutting board and dust the top with confectioners' sugar.
1 cup powdered sugar
Using a long thin knife brushed with vegetable oil and dusted with confectioner's sugar, cut marshmallow lengthwise into 6 strips, then crosswise into sixths (you should get about 36 squares total) or into a different size of your choice.
Coat marshmallows, one at a time, in confectioners' sugar and use a pastry brush to brush off any excess.
Store marshmallows in an airtight container layered between sheets of wax paper or parchment paper in a cool, dry place for up to a month.
Chocolate Graham Crackers
Combine flour, cocoa powder, brown sugar, baking powder, and salt in the bowl of a food processor and pulse to combine. Add butter and continue to pulse until mixture is the consistency of a coarse meal. If you don't have a food processor, you can do this in a stand mixer fitted with paddle, mixing on low. If you have neither, you can incorporate with a pastry blender (or even your fingers!).
2 cups all-purpose flour, ½ cup unsweetened cocoa powder, 1 cup dark brown sugar, 1 teaspoon baking powder, 7 tablespoons unsalted butter, ¾ teaspoon kosher salt
In a small bowl, whisk together honey, milk, and vanilla extract.
Add milk & honey mixture to the flour mixture and pulse on and off a few times or mix on low until the dough just comes together (being very careful not to over-mix). The dough should be soft and sticky.
Lay out a large rectangle of plastic wrap and dust it lightly with flour, then place dough on it and pat into a rectangle about 1-inch thick. Wrap dough and chill until firm, about 2 hours or overnight.
For round graham crackers:
(For an easier way to make the chocolate graham crackers, we found that you can make them into rounds rather than squares. Make them into dough balls using a cookie dough scoop, then use a sugar-coated glass to flatten the ball into a disk about 1/8 -inch thick.)
3 tablespoons granulated sugar
For square graham crackers:
Once chilled, divide dough in half and return one half to the refrigerator. On a flour-dusted surface, roll dough into a long rectangle about ⅛ inch thick, adding more flour as required.
The dough is very sticky, and best rolled out under a piece of plastic wrap.
Using a pastry cutter or a preferred tool, cut dough into 2" squares.
Prick each square with the end of a skewer, toothpick, or fork several times and place on parchment-lined baking sheets. Sprinkle with granulated sugar.
3 tablespoons granulated sugar
Chill squares in refrigerator until firm, about 30-45 minutes (you could also place in freezer for 15-20 minutes).
Repeat rolling and cutting with the second batch of dough and then gather dough scraps together into a ball, chill until firm, and re-roll. You should get about 48 2-inch squares.
While squares are chilling, pre-heat oven to 350° F.
Bake cookies for 15 to 25 minutes, until browned and slightly firm to the touch, rotating the sheets halfway through to ensure even baking.
S'mores Assembly
To assemble, place a mint marshmallow and chocolate square on a chocolate graham cracker.
24 squares of good-quality chocolate
Place the stack on a piece of parchment paper, and pop in the toaster oven for a minute or two until desired toasty-ness. Or place the stack on a microwave safe plate, and microwave on high for about 15 seconds.
Place the second chocolate graham cracker on top. Enjoy!
Notes
Makes: 24 s'mores (with some leftover marshmallows)