01 -
Preheat oven to 350°F (175°C) and grease a 9x13 inch baking pan.
02 -
In a large mixing bowl, whisk together flour, granulated sugar, baking powder, salt, and ground cinnamon until combined.
03 -
Add milk, melted butter, eggs, and vanilla extract to dry ingredients. Stir gently until just incorporated; avoid overmixing.
04 -
In a separate bowl, combine brown sugar, ground cinnamon, and softened butter until crumbly.
05 -
Spread half of the batter evenly into the prepared pan. Sprinkle cinnamon filling over the batter.
06 -
Pour remaining batter over the filling. Using a knife, gently swirl to create a marble effect without overmixing.
07 -
Combine flour, brown sugar, cinnamon, and salt in a bowl. Stir in melted butter and mix until crumbly.
08 -
Sprinkle crumb topping evenly over the batter in the pan.
09 -
Bake for 30-40 minutes or until a toothpick inserted in the center comes out clean.
10 -
Allow to cool for 10 minutes before slicing and serving.