01 - Preheat oven to 350°F. Lightly grease a 9x13-inch baking dish to prevent sticking.
02 - In a large bowl, combine the cake mix, eggs, milk, vegetable oil, and vanilla extract. Beat with a hand mixer for 2 minutes until the batter is smooth. Pour the mixture into the prepared baking dish and level the surface.
03 - Bake for 25 to 30 minutes until a toothpick inserted into the center emerges clean.
04 - While the cake is baking, mix the brown sugar and ground cinnamon in a small bowl. Stir in the melted butter to create a thick paste.
05 - After removing the cake from the oven, immediately use the handle of a wooden spoon to poke holes across the cake surface at 1-inch intervals. Spoon or drizzle the cinnamon filling over the hot cake, allowing it to soak into the holes. Let the cake cool completely.
06 - In a separate bowl, beat the softened cream cheese and butter until smooth. Add the powdered sugar, milk, and vanilla extract, then beat until the frosting is light and creamy.
07 - Spread the frosting evenly across the cooled cake. Cut into portions and serve.