In a mixing bowl, whisk together 240 g (1 ¾ cups) of the pancake mix with the sourdough discard.

Pour in the milk, melted butter, egg, and vanilla extract, stirring just until combined. (Lumps are fine! Overmixing leads to tough pancakes.)

Heat a well-seasoned cast iron skillet over medium heat and grease lightly with butter.

Pour batter onto the skillet, using about ¼ cup per pancake. Cook until bubbles form on the surface and the edges look set, then flip and cook until golden brown.

Serve warm with butter, real maple syrup, or a drizzle of honey.