Preheat oven to 350°. In a large saucepan, combine 1 cup sugar and cornstarch. Add raspberries; bring to a boil over medium heat. Cook 2 minutes, stirring constantly. Remove from heat; cool. , Meanwhile, combine biscuit mix, milk, eggs, oil and remaining sugar. Spread two-thirds of biscuit mixture into a greased 13x9-in. baking pan. Top with raspberry mixture, followed by remaining biscuit mixture. , For topping, combine pudding mix and sugar. Cut in butter until crumbly; sprinkle over batter. Bake until a toothpick inserted in the center comes out clean, 30-35 minutes.