Spray a 9-inch pie pan with nonstick cooking spray and set aside.
Place 2 cups of the Rice Krispie cereal in a medium mixing bowl.
In a microwave-safe bowl, combine 1 tablespoon of butter and approximately 1/3 of the 10-ounce package of marshmallows. Microwave in 20-second intervals, stirring after each interval, until melted and smooth.
Pour the melted marshmallow mixture over the 2 cups of Rice Krispie cereal. Stir until the cereal is evenly coated.
Press the mixture firmly into the bottom of the prepared pie pan, forming an even layer across the bottom and pressing it slightly thicker around the edges to create the crust.
Place the remaining 4 cups of Rice Krispie cereal in a large mixing bowl.
In a microwave-safe bowl, combine the remaining 2 tablespoons of butter and the remaining marshmallows. Microwave in 20-second intervals, stirring after each interval, until completely melted and smooth.
Add orange food coloring to the melted marshmallow mixture and stir until the desired bright orange color is reached.
Add the orange rice Krispies treats into the pie pan on top of the non-colored rice krispie treats. Press them down.
Pour the orange marshmallow mixture over the remaining 4 cups of Rice Krispie cereal. Stir gently until all of the cereal is evenly coated.
Transfer the orange Rice Krispie mixture to the pie pan and press it evenly over the crust layer.
Allow the Rice Krispie pie to cool at room temperature for 30 minutes to 1 hour. Do not refrigerate.
Cut the Rice Krispie treat into 8 slices like a pie. Top each slice with whipped cream before serving, if desired.