Step 1: Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper or silicone mats.
Step 2: In a large bowl, cream together the softened butter, granulated sugar, and light brown sugar with an electric mixer until light and fluffy.
Step 3: Beat in the light corn syrup and vanilla extract until well combined.
Step 4: In a separate medium bowl, whisk together the all-purpose flour, baking soda, salt, and old-fashioned rolled oats.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.
Step 6: Fold in the chopped pecans until evenly distributed throughout the dough.
Step 7: Drop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches between cookies.
Step 8: Bake for 10-12 minutes, or until the edges are golden brown and the centers are just set. They may still look slightly soft in the middle.
Step 9: Allow the cookies to cool on the baking sheets for 5-10 minutes before transferring them to a wire rack to cool completely.
Step 10: Store in an airtight container at room temperature for up to 3-4 days.