Coffee Cake

Scott went on a business trip to Florida a few months back.  His boss' wife made a homemade coffee cake for breakfast, and he came home talking about how wonderful it was.  I made him get the recipe, and he was right....It is GOOD!!  And EASY!!
Mix together one box of yellow cake mix, 4 eggs, 8 oz sour cream, and 3/4 cup of vegetable oil.  In a separate bowl, mix cinnamon and brown sugar.  In another bowl, mix 2 cups of powdered sugar with milk and vanilla flavoring for the icing.  Preheat your oven to 350.  Get out a 9 x 13 glass baking dish and spray with nonstick spray.  Put half the cake mixture in the pan then sprinkle with half of the sugar/cinnamon mixture.  Pour the rest of the cake batter then sprinkle again with the remaining sugar/cinnamon mixture.  Cook for 35 minutes.  Pour icing over your cake while it is still hot.  IT IS YUMMY!!  It gets even better the next day!!