Prepare the Crust

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Mix Ingredients: In a medium bowl, combine the graham cracker crumbs, melted butter, brown sugar, and cinnamon. Mix until well combined.
3. Press Into Pan: Press the mixture firmly into the bottom of a greased 9×13-inch baking dish. Bake for 10 minutes, then remove from the oven and set aside.

Make the Pumpkin Filling

1. Combine Filling Ingredients: In a large bowl, whisk together the pumpkin puree, granulated sugar, vanilla extract, cinnamon, nutmeg, ginger, salt, and eggs until smooth.
2. Pour Filling Over Crust: Pour the pumpkin mixture evenly over the pre-baked graham cracker crust.

Bake the Bars

1. Bake: Bake the bars in the preheated oven for 25 minutes, or until the filling is set and the edges are lightly browned.
2. Add Toppings: Remove from the oven and sprinkle the mini marshmallows and chocolate chips evenly over the top.
3. Finish Baking: Return to the oven and bake for an additional 5-10 minutes, or until the marshmallows are golden brown.

Cool and Serve

1. Cool: Allow the bars to cool in the pan for at least 15 minutes before slicing.
2. Slice and Enjoy: Cut into squares and serve warm or at room temperature.