Preheat the oven to 350F.

Spray a 9" pan with baking spray and set aside.

In a medium bowl, stir together the melted butter, brown sugar, and cinnamon for the topping until combined. Stir in the flour and chopped pecans. Set aside.

In another medium mixing bowl, stir together the cinnamon filling ingredients until combined. Set aside.

In a large mixing bowl, cream together the butter and sugar until light and fluffy, about 3-5 minutes.

Add in the eggs and vanilla extract and combine well.

Add in the sour cream, sourdough discard, and milk and whisk to combine.

Mix in the flour, salt, baking powder, and baking soda and whisk to combine, but do not overmix.

Pour half of the coffee cake batter into a prepared 9×9 cake.

Sprinkle the cinnamon sugar filling evenly over the cake batter in the pan.

Gently dollop the remaining cake batter over the cinnamon filling.

Use a spatula or offset knife to gently and evenly spread the cake batter over the filling.

Sprinkle the pecan crumble over the top of the cake batter.

Bake in a preheated oven for 40-45 minutes or until a toothpick inserted in the center comes out with minimal crumbs attached.

Cool on a wire rack until room temperature.