Preheat oven to 375°F (190°C). Line a standard-size baking sheet (with sides) with parchment paper or a baking mat.
In the bowl of a stand mixer (or a large mixing bowl with a hand mixer), cream the butter and sugars for 2 minutes or until light and fluffy. Add the eggs and vanilla extract, and beat until combined.
In a medium mixing bowl, whisk together the flour, salt, baking soda, and cinnamon. With mixing speed on low, gradually add the dry ingredients. Fold in 1 cup of mini marshmallows, the chocolate chips, and the mini chocolate chips.
Take the graham crackers and lay them out on the sheet until it's completely full (they should cover the entire sheet and cookies should be tight and touching—see picture above).
Using a standard cookie scoop, place one ball of dough onto each cracker. Use any remaining dough to fill in the gaps. It may look like a lot of dough, but it all needs to run together in order to cover the entire sheet.
Place in the oven and bake for 6-7 minutes, then remove and press Hershey's bar pieces into the top along with the remaining 1/4 cup marshmallows (just fill in the gaps with them a little). Return to the oven and bake for an additional 6-7 minutes or until dough and marshmallows begin to brown. Remove from oven and place sheet on a wire rack to cool. Once it is sufficiently cooled (20 minutes or so), place into the refrigerator to solidify. Remove after an additional 20 minutes and cut into squares.
Notes
STORE Graham S'mores Bars in an airtight container at room temperature for up to three days. For longer storage, FREEZE them in a single layer in an airtight container for up to three months.To REHEAT, place the bars in a preheated oven at 350°F (175°C) for 5-10 minutes until warm and gooey. Avoid reheating in the microwave, as it can make the graham crackers soggy.