How To make Pumpkin Tunnel Cake

1 1/4 c Brown sugar; firmly packed
1 c Pumpkin; cooked, mashed
1 1/2 ts Pumpkin spice mix
1/2 ts Maple flavoring
1 Egg; lightly beaten
1/4 c Vegetable oil
1 tb Vegetable oil
2 Egg whites
2 3/4 c All-purpose flour
1 1/4 ts Baking soda
1/4 ts Salt
1/2 c Oat bran
1 1/3 c Nonfat buttermilk
2 ts Vanilla extract
Vegetable cooking spray

GLAZE:

1/2 c Powdered sugar; sifted
2 ts Skim milk
1/2 ts Pumpkin pie spice
Combine 1/4 cup brown sugar and next 4 ingredients in a small bowl; stir well, and set aside. Combine remaining cup brown sugar and oil in a large bowl, beating well at medium speed of an electric mixer. Add egg whites; beat well. Combine flour and next 3 ingredients; add to brown sugar mixture alternately with buttermilk, beginning and ending with flour mixture. Mix after each addition. Stir in vanilla. Reserve 2 cups of batter, and set aside. Pour remaining batter into a 12-cup Bundt pan coated with cooking spray. Spoon pumpkin mixture evenly over center of batter to form a ring. Pour reserved batter over pumpkin mixture. Bake at 350~ for 50 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes; remove from pan. Cool on a wire rack. Combine powdered sugar and -----