Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking pan and set it aside.

In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, and salt until combined.

In another bowl, mix the milk, melted butter, eggs, and vanilla extract until well blended.

Gradually pour the wet mixture into the dry ingredients, stirring gently until combined. Be careful not to overmix!

In a small bowl, mix together the brown sugar, cinnamon, and softened butter until crumbly.

Pour half of the cake batter into the prepared pan. Evenly sprinkle the cinnamon swirl mixture on top, then pour the remaining cake batter over it.

Using a knife or a toothpick, gently swirl the cinnamon mixture into the cake batter to create a marbled effect.

Place the pan in the preheated oven and bake for 30 minutes or until a toothpick inserted in the center comes out clean.

While the cake is baking, cream together the softened cream cheese and butter in a mixing bowl until smooth.

Gradually add in the powdered sugar and vanilla extract, mixing until creamy.

Once the cake has cooled for about 10-15 minutes, spread the cream cheese frosting over the top and enjoy!