Drain pineapple, reserve 2/3 cup of the juice. Pat pineapple dry.
In medium bowl, stir together brown sugar, cinnamon, walnuts and butter; set aside.
In large bowl, beat baking mix, granulated sugar, egg and reserved juice for 30 seconds, until combined. Spoon into 9-inch round baking pan sprayed with nonstick vegetable cooking spray. Top with half of the walnut mixture, then pineapple and finish with remaining walnut mixture.