Mix dry ingredients: In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, granulated sugar, and salt until well combined.
Combine wet ingredients: In a separate mixing bowl, mix one cup of sourdough discard, milk, and beaten egg until smooth.
Combine wet and dry mixtures: Make a well in the center of the dry ingredients and pour in the wet mixture. Stir gently until just combined; it's okay if the batter is a bit lumpy. Do not overmix to ensure fluffy pancakes.
Add melted butter: Gently fold in the melted butter oil until just incorporated into the batter.
Preheat your pan: Heat a cast iron skillet or a hot griddle over medium heat. Brush with a thin layer of coconut oil to prevent sticking.
Cook pancakes: Pour 1/4 cup of batter onto the skillet for each pancake. Cook until bubbles form on the surface and the edges look set on the first side, about 2-3 minutes. Flip carefully and cook for another 1-2 minutes on the second side, or until golden brown and cooked through.
Serve warm: Serve the fluffy sourdough discard pancakes warm with your favorite toppings, such as maple syrup, fresh berries, or a dollop of butter.
Repeat: Continue with the remaining batter, adding more coconut oil to the skillet as needed.