Preheat the oven to 410 degrees (traditional bake & yes, that temp is correct!). Prep two large aluminum cookie sheets with parchment paper and set aside.
In a stand mixer fitted with a paddle attachment, whip up the butter until it's light an fluffy. Add in the sugars and cream together for 3 minutes. Scrape down the sides of the bowl with a spatula.
Add in vanilla and then one egg at a time (whipping up between additions).
Add in the flour, graham cracker powder, salt, baking soda, and cornstarch. Pulse until just combined (don't overmix!).
Either on the lowest speed possible, or hand stirring, (reserve a few pieces to press onto the outside of the cookie dough balls), add in the rest of the ingredients (chips, chunks, grahams, and mallows).
Split the dough in half, and then each half into 4 balls. Place 4 cookie dough balls the size of baseballs onto each cookie sheet (8 cookie dough balls total - yes, they're huge cookie dough spheres!). Press on chocolate chips for presentation, if desired.
Bake for 9 minutes. They should be mounded and toasty on the outside, but gooey on the inside. KEEP THEM ON THE PAN for 5 minutes to continue baking, pressing in the edges where needed to keep their circular shape around the sides, and then transfer them to a cooling rack to finish cooling.