Preheat your oven to 350°F (175°C) and grease a 9×13 inch baking pan.

In a medium bowl, whisk together flour, baking powder, salt, and ground cinnamon.

In a large bowl, cream together softened butter and granulated sugar until light and fluffy. Beat in eggs one at a time.

Gradually mix in the dry ingredients while alternating with milk until just combined.

Pour half of the batter into the prepared pan, sprinkle with half of the brown sugar-cinnamon mixture, then layer with the remaining batter and top with the rest of the mixture.

Bake for 30-35 minutes until golden brown and a toothpick inserted comes out clean.