Good-Cooking - Caramel Crater Cake

Ingredients

• 1 box Duncan Hines yellow cake mix
• 1 small box instant vanilla pudding
• 1/2 cup all-purpose flour
• 1/4 cup vegetable oil
• 2/3 cup water
• 2 eggs
• 1 teaspoon vanilla extract
• 1 teaspoon butter flavoring
• 1 cup firmly packed brown sugar
• 3/4 cup chopped walnuts
• 1 cup confectioners' sugar
• Enough milk to make thin glaze