To a large bowl, combine your starter, oil, sugar, eggs, sour cream, vanilla and milk. Use a whisk to stir this very well, until quite smooth.
In a medium bowl, combine your flour, cocoa powder, baking powder, baking soda and salt.
Incorporate your dry ingredients into the wet, and fold it in with a spindle or spatula until no dry bits are present. This consistency will be thick and fudgy. Fold in your chocolate chips here.
Cover and place into the fridge overnight to cold ferment and improve texture and moisture in the muffins!
Next day, remove your muffin batter from the fridge and prep your muffin tray. Either grease the tray cups well or use muffin liners.
Preheat your oven to 375 degrees.
Place about ¼ cup of batter into each cup. This is a thick batter! I like to place 6 cups dispersed into a dozen muffin tray, giving them space in between with empty muffin cups to help spread heat well and rise better. This is optional. You can fill all the muffin tray cups and these still rise and bake well!
Top with extra chocolate chips if desired and bake for 22-24 minutes.
Keep these at room temperature for 5 days in an airtight container or in the fridge for 10 days in an airtight container.
These also freeze and thaw well.
