Preheat the oven to 375 degrees. In a medium sized mixing bowl, sift together the flour, baking powder, soda, salt, and espresso powder.
2 Cups All Purpose Flour, 1 tsp kosher salt, 2 tsp baking powder, 1 tsp soda, 1/2 tsp espresso powder
In a separate bowl, mix together the buttermilk, cocoa powder, and melted butter. Then add in the sourdough starter discard and the vanilla extract.
2/3 Cup cocoa powder, 1- 1/4 Cup buttermilk, 1 stick melted butter, 1/2 Cup sourdough starter discard, 2 tsp vanilla
In a separate bowl, combine the sugar and eggs and whisk until light and creamy. Then, add both the sugar-egg mixture and the chocolate-buttermilk mixture into the flour and mix until all the ingredients are incorporated. Then, fold in the chocolate chips so that they are evenly dispersed throughout the batter.
1 Cup sugar, 3 eggs, 1- 1/2 Cup chocolate chips
At this point you can prepare to bake the muffins immediately OR cover the batter and allow it to ferment in the refrigerator overnight before baking.
Prepare your muffin pan by greasing the trays with softened butter OR by filling them with cupcake liners. Move your oven rack to the center of your oven and preheat the oven to 375 degrees.
Place the prepared muffin tin into the preheated oven to bake for 15 minutes or until a toothpick comes out clean.