Heat oven to 350º. Heat 1/2 cup brown sugar, the margarine and syrup in 1-quart saucepan over low heat, stirring occasionally, until melted. Pour into ungreased rectangular pan, 13x9x2 inches.
Beat remaining ingredients in medium bowl, using wire whisk or fork, until blended. Carefully pour over syrup mixture.
Bake uncovered 30 to 35 minutes or until top springs back when touched in center. Cut into 3-inch squares; turn each square upside down onto plate. Serve immediately, with maple-flavored syrup.