1 package yellow cake mix
4 large eggs
2/3 cup vegetable oil
1/3 cup water
1 (8 ounce) container sour cream
1/2 cup firmly packed brown sugar
1 tsp. ground cinnamon
2/3 cup chopped pecans or walnuts
1 cup sifted powdered sugar
1 tbsp. + 1 tsp. milk
1/2 tsp. vanilla extract
Combine first 5 ingredients in mixing bowl; beat at medium speed with an electric mixer 2 minutes. Set aside. Combine brown sugar, cinnamon, and nuts; set aside.
Pour half of batter into greased and floured 9×13 cake pan. Sprinkle half of sugar mixture over batter. Repeat with remaining batter and sugar mixture. Gently swirl batter with a knife.
Bake at 350 degrees for 35 minutes or until a toothpick inserted in center comes out clean.
Combine glaze ingredients until smooth. Drizzle over cake, and cool.