1Heat oven to 350° F. Spray bottom only of 13x9-inch pan with cooking spray.
2Make brownie mix as directed on box for fudge brownies, using water, oil and eggs. Stir in chopped pecans. Bake as directed. Cool completely, about 1 hour.
3In medium saucepan, mix cream, butter and brown sugar. Cook over medium heat, stirring frequently, until mixture comes to a boil. Continue cooking 1 minute, stirring constantly. Remove from heat. Stir in pecans, powdered sugar and vanilla. Cool 5 minutes, stirring frequently.
4Spread frosting over brownies. Allow to stand 30 to 45 minutes, or until frosting is set. For bars, cut into 6 rows by 4 rows.