To make the treats: Lightly coat a 9x13-inch pan with butter, oil, or cooking spray; set aside.
In a large bowl, combine the cereal and marshmallow bits (if using); set aside.
In a large pan, melt the butter over medium-low heat. Add the marshmallows and stir constantly to melt them. When they are almost completely melted, stir in the orange zest. As soon as the marshmallows are completely melted, remove from heat and stir in the cereal. Make sure to get it completely coated with the marshmallow mixture.
Press the mixture into the prepared pan, making sure it is spread evenly. Don't press it too firmly, or the treats may set up very hard.
Allow the treats to set up for at least 10 minutes, then use an empty push-up pop container, or a small round cookie cutter, to cut out enough round treats to fill each push-up pop container with three. For example, for 6 push-up pops, you'll need 18 round treats (three for each container). Allow the circles to continue setting up while you make the frosting.
To make the frosting: In a large bowl, or the bowl of a standing mixer, beat the butter for 3 minutes. Beat in the sugar until combined. Add 2 tablespoons heavy cream and whisk on high for 4 minutes, until light and fluffy. Stir in the zest, juice, and food coloring.
Assemble: In each push-up pop container, press a round treat into the bottom of the container. Pipe a small amount of frosting on top of it, then, press another treat over the frosting. Add more frosting on top of this treat, and press one more treat on top. Pipe a rosette of frosting on top, and garnish with sprinkles or candies.