Step 1

Preheat oven to 375 degrees Fahrenheit.

Step 2

Melt butter in cast iron skillet or large saucepan over medium low heat.

Step 3

Add chocolate chips and stir until melted.

Step 4

Remove skillet from heat. Whisk in eggs, sugar, vanilla, and salt until fully combined.

Step 5

Add sourdough starter and mix.

Step 6

Add cocoa powder and whisk until fully combined.

Step 7

Sprinkle baking soda over batter and whisk again until thoroughly mixed.

Step 8

Transfer to glass baking dish if not using cast iron and bake in preheated oven for 20 minutes.

Step 9

Cool completely before cutting and serving. (unless you don't mind crumbly brownies!)

Step 10

Store leftovers in the refrigerator for up to 5 days.