Preheat your oven to 350° Fahrenheit (176° Celsius).
In a medium mixing bowl, combine melted butter, brown sugar, vanilla extract.
One at a time, whisk in the eggs.
Stir in the sourdough starter discard.
In a smaller mixing bowl, whisk together the flour and salt.
Add the dry ingredients to the wet ingredients and stir until just moistened.
Fold in the chocolate chips.
Pour into a lightly greased 8-inch by 8-inch baking pan and bake for 50 to 60 minutes. A toothpick inserted into the middle should come away clean.
Allow to cool to room temperature before slicing and removing from the pan.
Notes
These blondies will stay fresh for a few days at room temperature. However, you can freeze leftover blondies for later. Just be sure to layer them with parchment paper or wrap them in plastic wrap to prevent sticking.