Combine the cup of starter, egg, buttermilk, and melted butter in a small bowl.
In a separate bowl, gently combine the dry ingredients: flour, sugar, baking powder, and salt.
Stir the wet mixture into the dry mixture and mix together until you have a smooth batter.
Allow the batter to rest for at least 10 minutes.
Prepare a cast iron skillet or griddle by greasing it with butter and putting it on medium-low heat.
Once the pan is nicely heated, put ⅓ cup batter per pancake onto the skillet. (If you’re using a griddle, you can cook more than one pancake at once.)
Cook for about 3 minutes, until the edges are done and the center is bubbling, before flipping the pancake. Cook the other side for around one and a half minutes until the pancake is golden brown.
If you’re making several pancakes, slide the cooked pancakes into the oven on a low setting to keep warm until you’re ready to serve up.