This cake is seriously amazing!
1 pkg yellow cake mix
2 sticks butter, softened
1 (8oz) container sour cream or plain yogurt
½ c packed brown sugar
1/3 cup chopped pecans, optional
2 tsp. cinnamon
1 c powdered sugar
1 tbs. milk
1 tsp. vanilla
Preheat oven to 350o. Generously grease bottom only of 9x13 pan. Remove ½ cup dry cake mix; reserve. Beat remaining dry cake mix, butter, eggs and sour cream in large bowl on medium speed for 2 min; scraping bowl occasionally. Spread half the patter into pan. Stir together reserved dry cake mix, brown sugar, pecans and cinnamon; sprinkle over batter in pan.
Carefully spread remaining batter evenly over pecan mixture. (To make easier drop batter by dollops over pecan mixture, then spread) Bake 30 min or until deep golden brown and cake springs back when touched lightly in center. Stir powdered sugar, milk and vanilla until thin enough to drizzle, stirring in additional milk, 1 teaspoon at a time if necessary. Poke top of warm cake several times with a fork; spread glaze over top of cake. Cool completely about 1 hr. or serve warm. Store Covered.