01 -
Heat oven to 350°F and grease a 9x13-inch baking dish.
02 -
Mix flour, sugar, baking powder, and salt in a large bowl.
03 -
Add milk, eggs, vanilla, and melted butter to dry ingredients.
04 -
Stir until smooth.
05 -
In a separate bowl, mix softened butter, brown sugar, flour, and cinnamon.
06 -
Pour cake batter into prepared dish.
07 -
Drop spoonfuls of cinnamon mixture over batter.
08 -
Swirl with a knife to create a marble effect.
09 -
Bake 30-35 minutes until a toothpick comes out clean.
10 -
Mix powdered sugar, milk, and vanilla for the glaze.
11 -
Pour glaze over the slightly cooled cake.
12 -
Let glaze set before serving.