1Heat oven to 350°F (325°F for dark or nonstick pan). Grease bottom only of 13x9-inch pan with shortening or cooking spray.
2In 2-quart saucepan, melt butter over medium-low heat. Stir in flour until smooth. Stir in brown sugar, corn syrup and 2 eggs until well blended. Increase heat to medium; cook 3 to 5 minutes, stirring constantly, until mixture just begins to boil. Remove from heat; stir in vanilla and pecans.
3Make brownie batter as directed on box for cakelike brownies; spread in pan. Spoon pecan topping evenly over batter.
4Bake 33 to 38 minutes or until center is set. Cool completely, about 3 hours. For 36 brownies, cut into 6 rows by 6 rows. If desired, garnish each brownie with a pecan half.