Preheat oven to 350 degrees F°. Spray a 9×13-inch glass baking dish with cooking spray. Set aside.
Cinnamon Roll Cake
In an electric stand mixer, add the flour, salt, sugar, baking powder, milk, eggs, and vanilla. Mix until just combined. Slowly mix in melted butter. Pour batter into the prepared pan, spreading out evenly.
Cinnamon Swirl Topping
In a large bowl, mix the butter, brown sugar, flour and cinnamon together until well combined and creamy. Drop tablespoons of the topping evenly over all of the batter. Use a knife to marble/swirl topping throughout the cake.
Bake cake for 32 to 38 minutes, or until a toothpick inserted in the center comes out nearly clean. Carefully remove cake from oven and let stand at least 15 minutes before topping with glaze.
Vanilla Glaze
In a medium bowl, mix the powdered sugar, milk and vanilla together with a whisk. Drizzle evenly over the warm cake. Slice and serve warm or at room temperature. Enjoy!