Preheat your oven to 375°F (190°C) and line a 9x13-inch baking pan with parchment paper.

Arrange graham crackers in a single layer across the bottom of the prepared pan.

In a bowl, cream together butter, granulated sugar, and brown sugar until light and fluffy. Mix in eggs and vanilla extract.

In another bowl, whisk together flour, baking soda, and salt. Fold this into the wet mixture along with chocolate chips and mini marshmallows.

Spread the cookie dough evenly over the graham cracker base.

Bake for 25-30 minutes until edges are golden brown and a toothpick comes out clean.

Lay Hershey’s chocolate bars across the top while still warm.

Let the bars cool in the pan for 10-15 minutes, then slice into squares.