Measure out the sourdough starter in a medium-sized mixing bowl.
Add in the two eggs, melted butter, and a dash of salt. Mix together with a spatula.
Slowly pour the milk mixture into the bowl as you continously whisk. The matter should be thin and smooth.
Heat up a cast-iron skillet over medium heat. If you use a 10" skillet, you'll be able to make 4 crepes. If you use a 12" skillet, you'll only get 3 crepes.
Melt some butter in the pan to coat. For a 10" skillet, pour in 1/3 cup of batter into the pan. For a 12" skillet, pour 1/2 cup of batter into the pan. Immediately swirl the crepe batter around the pan so the entire bottom is covered in it, so you can get that perfect circle shape.
Cook on the first side for 2-3 minutes. The bottom should get nice and golden.
The crepe is ready to flip when you can easily get a spatula underneath it. Flip it and cook on the other side for 30 to 60 seconds—until the other side is golden brown.
Serve immediately with fresh berries, syrup, or any other desired fillings!