Preheat the oven to 300 degrees. Generously grease two baking sheets of the same size with nonstick cooking spray, making sure the entire surface is well coated to prevent sticking.
Add the rice cereal and pecan halves to a large mixing bowl. Set aside.
Place the unwrapped caramels and milk into a saucepan. Heat over low heat, stirring frequently, until the caramels are completely melted and smooth. This will take several minutes. Keep the heat low to avoid burning the caramel.
Pour the melted caramel mixture over the cereal and pecans. Stir thoroughly until all pieces are evenly coated. Spread the coated mixture onto one prepared baking sheet in an even layer. Bake for 15 minutes.
Remove the pan from the oven and gently flip and toss the mixture to redistribute the caramel. Return to the oven and bake for an additional 15 minutes.
Remove the pan from the oven. Place the second prepared baking sheet on top of the hot pan. Holding both pans together with oven mitts, carefully flip them so the clusters fall onto the clean baking sheet. Remove the original pan and allow the clusters to cool completely.
Once fully cooled, break into clusters and serve or store in an airtight container.
Notes
You can also use parchment paper to help the release and transfer of pecan clusters.