In a large mixing bowl, whisk together the all-purpose flour, sugar, baking powder, and salt until well combined.

In a separate bowl, cream the softened butter until smooth, then add the eggs, milk, and vanilla extract, mixing until fully incorporated.

Gradually combine the wet and dry ingredients until just blended, ensuring not to overmix.

In a small bowl, combine the brown sugar, ground cinnamon, and melted butter, stirring until it resembles a thick paste.

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

Pour half of the prepared cake batter into the greased pan, spreading it evenly. Drizzle half of the cinnamon mixture over the batter.

Add the remaining batter on top and finish with a drizzle of the remaining cinnamon mixture, gently swirling with a knife.

Bake the cake for 35-40 minutes until a toothpick inserted in the center comes out clean.

While the cake is baking, prepare the glaze by whisking together powdered sugar, milk, and a touch of vanilla extract.

Drizzle the prepared glaze generously over the warm cake.

For added flavor, consider topping with toasted pecans or a sprinkle of cinnamon before serving.