Blend brown sugar and cinnamon in a small bowl and set aside. Stir
together cake mix, sour cream, eggs and oil.
I just whisked it all together, lumps are fine. Spoon half of your
batter into a greased or sprayed 9 x 13 pan (or something close)
Spread to the edges. Sprinkle brown sugar mixture over top, it'll
seem like a lot but use it all.
Spoon remaining batter over top, try to cover top evenly but don't
try to spread it. Using a knife, swirl batter, just run the knife in a
Bake in a preheated 350 degree oven for 40-45 minutes, until a
toothpick comes out clean.
While cake is baking, mix up your glaze. Combine powdered sugar,
milk and vanilla until smooth. Once cake is done, remove from oven
and drizzle glaze over top.
Let set for five long minutes before cutting and serving.