Line a 13- by 9-inch pan with foil, leaving enough overhang to use as handles. Coat the foil with cooking spray.
Melt the butter in a large saucepan over low heat. Stir in the orange zest, vanilla extract, and orange extract. Tilt the pan to coat the inside with the melted butter. Using a silicone spatula (to prevent sticking), gradually add the marshmallows, stirring until completely melted, 6 to 8 minutes. Remove from the heat and stir in the rice cereal until completely coated.
Scrape the mixture into the prepared pan, quickly spreading it with the spatula or covering it with wax paper and using your hands to spread it evenly (the mixture will be sticky). Cool completely; then use the foil handles to remove the entire pan of treats to a cutting board. Cut into 2-inch squares and serve immediately.
Tip: Be sure to use marshmallows well within their expiration dates. Old ones will not melt properly. To freeze the treats, place them in layers separated by wax paper in an airtight container in the freezer for up to six weeks. Let them stand at room temperature for 15 minutes before serving. For a flavor twist, add ½ teaspoon of ground cardamom or cinnamon. For super-thick treats, use a 9-inch square pan.