Honey Bun Cake

I made this cake as a surprise for my husband's birthday and he has officially proclaimed it his new favorite cake. It was an upsetting defeat for Carrot Cake, the previous title-holder, but the verdict was undisputed as the decadent, buttery layers of this cake and the ribbon of cinnamon and pecans are equally charming and irresistible. Likewise, this cake is most definitely NOT good for you, but deep down you know that acknowledging that would spoil the fun.
The recipe came off of the back of a Betty Crocker cake mix box, but I've tweaked it slightly.

1	box Betty Crocker® SuperMoist® Butter Pecan cake mix
1 cup butter	or margarine, room temperature
4	eggs
1	container (8 oz) sour cream (1 cup)
1	cup packed brown sugar
1/3	cup chopped pecans
2	teaspoons ground cinnamon
1	cup powdered sugar
1	tablespoon milk
1	teaspoon vanilla

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1.	Heat oven to 350°F (325°F for dark or nonstick pan). Grease with shortening and lightly flour 13x9-inch pan, or spray with baking spray with flour.
2.	In large bowl, beat dry cake mix, oil, eggs and sour cream with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. It will be extremely thick. Spread half of the batter in pan.
3.	In small bowl, stir together brown sugar, pecans and cinnamon; sprinkle over batter in pan. Carefully spread remaining batter evenly over pecan mixture. This is easiest to accomplish if you drop the batter in dollops over the top and then spread.
4.	Bake 44 to 48 minutes or until deep golden brown. In another small bowl, stir powdered sugar, milk and vanilla until thin enough to spread. Prick surface of slightly cooled cake several times with fork. Spread powdered sugar mixture over cake. Cool completely, about 1 hour. Store covered at room temperature.
High Altitude (3500-6500 ft): Bake 46 to 50 minutes.