preheat oven to 350. coat a 9x13 inch baking dish with cooking spray.
in a large bowl, prepare brownie mix according to package directions. pour into prepared baking dish. in a medium bowl, combine the corn syrup, vanilla, brown sugar, and pecans, mix well. drop the pecan mixture by spoonfuls into the batter.
bake 35 to 40 minutes or until toothpick inserted in the center comes out dry. cool, then cut into squares.