
This sourdough discard coffee cake is rich and buttery. Fluffy vanilla cake brimming with cinnamon sugar, it's the perfect easy sourdough breakfast for a crowd.
Stir the brown sugar, flour, and cinnamon together in a bowl. Add the melted butter and mix to combine. Set aside.
Preheat your oven to 375℉ (190℃). In a large mixing bowl, cream together butter and sugar. Add vanilla extract, eggs, milk, and sourdough discard (or active starter). Mix to combine.
Add the baking powder and flour and mix until combined.
Generously grease a 9x13 pan and pour half of the coffee cake batter into the bottom. Layer half of the cinnamon sugar all over the pan and pour the remaining batter on top. Crumble the remaining cinnamon sugar mixture on top.
Bake for 40-45 minutes at 375℉ (190℃) until the top is golden brown and a toothpick inserted into the middle comes out clean. Allow to cool in the pan before slicing. Serve and enjoy!