Mix buttermilk, cornmeal, egg, butter, salt, and baking soda in a bowl until just combined.
Heat a griddle or large skillet over medium heat. Spray with non-stick cooking spray. Drop by heaping tablespoonful onto the griddle. Cook until bubbles form on the top, 2 to 3 minutes; flip and brown on the other side, another 2 to 3 minutes.