Set the sugar in a large bowl and add the eggs. Immediately begin beating with a hand mixer (a whisk can work too but you’ll need to put some muscle into it) until light and fluffy. This can take up to 3 minutes. Add the sea salt and vanilla while beating.

With the mixer on, slowly pour in the melted butter, beating until smooth and combined.

Add the sourdough discard and beat to combine. Beat in the cocoa, then add the flour and with the mixer on, pour in the buttermilk or kefir. Beat to just combine. Fold in the chocolate chips.

Line two 12 cup muffin pans with 12 liners, skipping every other one so that no two muffins will bake next to each other. You should have enough batter for 12 muffins total. Divide the batter between the cups, filling them about three quarters full. Top with more chocolate chips, if desired.

Set the trays in the fridge and preheat the oven (the muffins don’t need to be in there that long, just for 5-10 minutes, and it isn’t strictly necessary but it does give them some height) to 400 F. Bake the muffins in the center rack. After 7 minutes of bake time, lower the temperature to 350 F. Bake until the tops spring back or a cake tester comes out clean, about another 12-15 minutes. Let cool then remove from pan.