Preheat oven to 350°. Grease a 9 x 13-inch baking pan with baking spray or line with parchment paper.
In a large bowl, beat brown sugar, butter, syrup and vanilla until blended. Beat in eggs. In another bowl, whisk flour, salt and baking soda; gradually beat into brown sugar mixture.
Transfer batter to prepared pan. Bake 22-30 minutes or until golden brown and a toothpick inserted in center comes out with moist crumbs.
Meanwhile, in a small saucepan, melt butter over medium-low heat; stir in syrup and brown sugar. Bring to a boil over medium heat; cook and stir 2-3 minutes or until slightly thickened. Remove from heat; cool slightly.
Pour glaze over warm cake. Cool completely in pan on a wire rack. Cut into bars.