Preheat your oven to 425F and prepare a 12-muffin pan with muffin liners.
In a large mixing bowl, mix the wet ingredients in a medium mixing bowl. (oil, sugar, milk, eggs, sour cream, sourdough discard, vanilla extract)
In a separate bowl, mix the flour, baking powder, baking soda, cocoa powder, and salt.
Add the dry ingredients to the large mixing bowl containing the wet ingredients. Whisk until combined. Stir in the chocolate chips.
Using a 3-tablespoon cookie scoop, divide the muffin batter through the prepared 12-muffin pan. Bake at 425F for 5 minutes and 350F for 12-15 minutes or until the muffins are domed and slightly firm to the touch. When changing the temperature of the oven, do not open the door.
Notes
Tip: if you are wanting to long ferment these muffins to enhance the sourdough flavor and benefits, make sure you add the baking powder and baking soda last (right before baking).Tip: Take the muffins out of the oven when they look just done (no wet batter on top) the idea here is to catch them when they are just fully baked but before they are overbaked. If you take them out before the tops are set, however, they could potentially sink while cooling.Tip: For the best and most consistent results, use a kitchen scale to weigh your ingredients.