Follow these simple steps to create your Easy Cinnamon Roll Cake:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
2. Mix Dry Ingredients: In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt until well combined.
3. Combine Wet Ingredients: In another bowl, whisk together the milk, vegetable oil, eggs, and vanilla extract until smooth.
4. Combine Mixtures: Pour the wet ingredients into the dry ingredients. Stir until just combined, being careful not to overmix.
5. Prepare Cinnamon Mixture: In a small bowl, mix together the ground cinnamon and brown sugar. Set aside.
6. Layer the Batter: Pour half of the cake batter into the prepared baking pan, spreading it evenly.
7. Add Cinnamon Mixture: Sprinkle the cinnamon and sugar mixture over the batter, followed by the melted butter. Drizzle the remaining batter over the top, spreading it gently.
8. Swirl the Batter: Use a knife or skewer to swirl the cinnamon mixture into the batter for a marbled effect.
9. Bake: Place the baking pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
10. Cool the Cake: Remove the cake from the oven and let it cool in the pan for 10-15 minutes before transferring it to a wire rack to cool completely.
11. Make the Icing: In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth. Adjust the consistency as needed.
12. Drizzle the Icing: Once the cake is cool, drizzle the icing over the top for a sweet finish.

With these straightforward steps, you’ll have a delightful Easy Cinnamon Roll Cake ready to enjoy!