Preheat oven to 375°
Mix brown sugar, flour, cinnamon, and melted butter together and set aside
Cream butter and white sugar
Mix in eggs, vanilla, milk, and sourdough
Mix in baking powder and flour
Grease 9x13 pan
Pour half batter into pan
Sprinkle half cinnamon mixture over batter
Add remaining batter
Top with remaining cinnamon mixture
Bake 40 to 45 minutes until golden and set
Cool slightly then slice
