Preheat the oven to 350°
Make the yellow cake mix according to the directions on the back of the packaging but replace the water with milk.
Add the mixture to a 9” x 13” baking dish thats been sprayed with cooking spray.
In a small bowl, mix together the softened butter, brown sugar, flour and cinnamon.
Add dollops of the brown sugar mixture to the top of the cake mix and using a butter knife, swirl the brown sugar mixture into the cake.
Bake the cake for 30 minutes or until the cake is cooked all the way through.
In a small bowl, whisk together the powdered sugar, milk and vanilla and pour the glaze over the warm cake.
Finally, let it cool, and serve at room temperature and enjoy!