Step 1

Melt the butter in a bowl and stir in the light brown sugar and cinnamon until smooth. Add the flour and pecans and stir again until the mixture comes together into a big clumpy mass. Set it aside and let it cool.

Step 2

Stir the cinnamon, flour and light brown sugar together in a small bowl and set aside.

Step 3

Preheat your oven to 350°F (175°C). Lightly grease an 9" x 9" metal baking pan with butter or cooking spray.

Step 4

In a large mixing bowl, use a spatula to cream the butter, light brown sugar and granulated sugar until smooth. Add the eggs, vanilla extract, sour cream, sourdough starter, milk, salt and baking powder to the bowl and stir until combined. Add the flour and mix until ingredients are fully incorporated.

Step 5

Pour half of the cake batter into the greased baking dish. Sprinkle the cinnamon sugar mixture evenly across the surface of the batter. Carefully pour the remaining batter over the cinnamon sugar mixture to cover. Use an offset spatula to gently spread the batter evenly. Break up the crumble topping with your fingers and sprinkle evenly over the top.

Step 6

Bake for 40-45 minutes or until a toothpick inserted in the middle comes out clean.