Prepare Your Pan: Lightly spray a 13x9 inch baking dish with non-stick spray and set it aside. This helps prevent sticking and makes cleanup a breeze!
Melt the Gooey Base: In a large microwave-safe bowl, combine the jumbo marshmallows and cubed butter. Microwave for 60 seconds. Remove the bowl and stir well until the mixture is completely melted and smooth. If you need a little more time, microwave in additional 20-second intervals until perfectly smooth.
Add Flavor: Stir in the vanilla extract until it's fully combined with the warm marshmallow mixture, adding a lovely aroma.
Mix in the Crunch: Add the Golden Grahams cereal to the bowl. Gently fold everything together until all the cereal is beautifully coated with the marshmallow goodness.
Fold in the Fun: Carefully stir in the mini marshmallows and semi-sweet chocolate chips. Mix until they are evenly distributed throughout the cereal, ensuring a bite of s'mores in every piece!
Press into the Pan: Transfer the entire mixture to your prepared baking dish. Grab a spatula, lightly spray it with non-stick spray, and press the mixture down firmly into an even, compact layer.
Top it Off: Arrange the broken Hershey's chocolate pieces over the top of the bars. Gently press them into the surface so they stick, adding that classic s'mores finish.
Chill and Enjoy: Let the bars cool and set at room temperature for about 2 hours before slicing them into delicious, ready-to-eat treats. No refrigeration needed!