Line a 8- or 9-inch square pan with parchment paper and spray with cooking spray.
Heat butter in the microwave in a large microwave-safe bowl until melted.
Stir the marshmallows, the extracts, and the milk into the melted butter until the marshmallows are coated with the butter mixture.
Microwave the mixture in 30 second bursts, stirring in-between, until the mixture is smooth.
Stir in the rice cereal until well mixed. Allow the mixture to cool for 2 minutes and then add in the sprinkles. Stir until well distributed.
Transfer the mixture to the prepared pan and press down with greased fingers until the mixture is in a flat layer. Add additional sprinkles over the top, if desired.
Cool the bars for at least 30 minutes at room temperature. Remove the batch from the pan using the parchment paper and slice into 16 squares using a sharp knife over a cutting board.
Notes
To prepare a rice krispie cake in a Bundt pan:Grease the Bundt pan generously with cooking spray, making sure to cover the center core and all edges. Transfer the marshmallow and cereal mixture into the pan, pressing down on the mixture to ensure even contact with the pan. Cool for 30 minutes and gently slide a small spatula along the edges to loosen them before inverting the cake onto a serving platter.
Nutrition facts are sometimes provided below and are calculated using an online calculator. With specific brands of ingredients and additions, omissions, or substitutions the nutrition facts may change. We encourage you to use your own nutrition facts calculator to obtain the most accurate nutrition facts for your meal.