Heat oven to 350℉. Spray a 16" round pizza pan with cooking spray. Set aside. * NOTE : Don't preheat the oven yet. The dough has to refrigerate for 1 hour, which is when you can preheat the oven. In a small mixing bowl, whisk together the flour, graham cracker crumbs, baking soda, and salt.
2 cups all-purpose flour, 1 cup graham cracker crumbs, ½ teaspoon baking soda, ½ teaspoon salt
In a separate mixing bowl ,using a stand mixer or hand mixer, cream together the butter, brown sugar, and sugar on medium-high speed until the mixture is fluffy and much lighter in color (this will take about 3 minutes).
1 cup (2 sticks) unsalted butter, 1 cup packed light brown sugar, 1/2 cup granulated sugar
Mix in the eggs, one at a time, until they are completely incorporated. Mix in the vanilla extract.
2 large eggs, 2 teaspoons vanilla extract
Add the dry ingredients into the dough and mix on low speed just until combined and no flour pockets or streaks remain.
Lightly wet your hands (not dripping wet but slightly moist) and press the dough onto the pizza pan, leaving a 1-inch edge around the whole pan. Cover the pizza with plastic wrap and refrigerate for 1 hour before baking. * Don't skip this! The dough needs time to firm up again and chill so it does not spread too quickly while baking. Bake for 22-25 minutes or until the crust is golden brown.
Remove the pizza from the oven and sprinkle the milk chocolate chips over the crust. Place it back into the oven for 1 minute. Spread the melted chocolate all around the cookie crust, leaving 1/2 inch around the edge so you can see the crust. * You can turn the oven off at this point and set it to a low broil for the next step. 1½ cups Hershey's milk chocolate chips
Evenly sprinkle the mini marshmallows over top the melted chocolate. Broil on low for a few minutes just until the marshmallows are toasted and golden brown. * Keep a close eye on it cause it will burn quickly. 2 cups mini marshmallows
Garnish the top of the pizza with the broken Hershey chocolate bar pieces and graham cracker pieces. * You can also sprinkle some graham cracker crumbs over top or the garnish if you don't have whole graham cracker sheets. 2 bars (1.55 oz) Hershey chocolate bars, 1 graham cracker sheet