Step 1: Line a baking sheet or cutting board with parchment paper. Lightly grease your hands or use cooking spray, as the mixture will be sticky.
Step 2: In a large microwave-safe bowl, combine the mini marshmallows and caramel sauce. Microwave on high for 1 minute, then stir well. Continue microwaving in 30-second intervals, stirring after each, until the marshmallows are mostly melted and the mixture is smooth. (Alternatively, you can melt these in a saucepan over low heat, stirring constantly).
Step 3: Add the chopped pecans to the marshmallow-caramel mixture. Stir vigorously until the pecans are evenly coated.
Step 4: Transfer the mixture onto the prepared parchment paper. Using your greased hands or another piece of parchment paper to press, shape the mixture into a log about 8-10 inches long and 2-3 inches in diameter. Press firmly to ensure it holds together.
Step 5: Wrap the pecan log tightly in the parchment paper, then transfer it to the refrigerator. Chill for at least 2 hours, or until completely firm.
Step 6: Once chilled, unwrap the log and slice it into 1/2-inch thick rounds using a sharp knife. Serve immediately or store for later.