Preheat your oven to 350°F (175°C).

Grease a 9x13-inch baking pan generously with non-stick butter spray.

In a medium bowl, combine the graham cracker crumbs, powdered sugar, and melted butter. Stir well.

Press the crumb mixture evenly into the bottom and up the sides of the prepared pan.

Place the crust in the preheated oven and bake for 5-8 minutes until golden brown.

Once baked, remove the pan from the oven and let the crust cool slightly for about 5 minutes.

Unwrap the Hershey chocolate bars and place them evenly on top of the warm crust.

Return the pan to the oven for about 3 minutes, until the chocolate is shiny and begins to melt.

Allow the chocolate to cool for 1-2 minutes, then pack the mini marshmallows closely on top.

Switch your oven to broil, and broil the marshmallows for about 2 minutes until golden brown.

Let the S’mores Bars cool completely at room temperature.

Using a warmed knife, cut the cooled S’mores Bars into squares or rectangles.