01 -
Heat your oven to 350°F. Using an electric mixer, beat together your cake mix, eggs, water, oil, and sour cream for 2 minutes, scraping down the bowl halfway through. Pour this into a greased 9x13 pan.
02 -
Mix your brown sugar, cinnamon, and pecans (if using) together. Sprinkle this evenly over the batter, then take a butter knife and swirl it all together until the brown sugar starts sinking into the batter.
03 -
Mix up the topping by combining more brown sugar and cinnamon, then sprinkle this over everything.
04 -
Pop it in the oven for 35-45 minutes. You'll know it's done when a cake tester or toothpick comes out clean from the center.
05 -
While the cake bakes, whisk together the powdered sugar, milk, vanilla, and salt until smooth. Pour this glaze all over the cake as soon as it comes out of the oven.
06 -
Cover the hot glazed cake with foil and let it cool completely. This helps keep all that moisture and sweetness locked in.