Method
Preparation
Preheat oven to 350°F (175°C). Grease a 9x13 inch pan.
In a bowl, whisk together flour, sugar, baking powder, and salt.
In another bowl, mix milk, melted butter, egg, and vanilla.
Pour wet mix into dry mix. Stir until smooth.
Pour batter into the prepared pan and spread evenly.
Mix brown sugar and cinnamon. Stir in melted butter to make a paste.
Cinnamon Swirling
Drop spoonfuls of the cinnamon mixture over the batter.
Use a knife to swirl the cinnamon through the batter.
Baking
Bake 25-30 minutes or until a toothpick in the center comes out clean.
Cool for 10 minutes.
Mix glaze ingredients until smooth and drizzle over warm cake.
Let cool a bit more, then slice and serve.
Notes
Use room temperature milk and egg for a smooth batter. Do not overmix. Make clear swirls but avoid overworking the batter. Cover lightly with foil if the top browns too fast.