Preheat the oven to 160C/320F. Grab a 9" x 9" brownie pan - it's up to you whether you grease the pan with butter or line it with parchment paper.

In a bowl, add the all purpose flour, white sugar, cocoa powder, salt and baking powder. Whisk the dry ingredients together until well combined.

Place the chocolate chips in the bowl and mix until they are all coated in the flour mixture.

In a separate bowl, add the melted butter, 2 eggs, vanilla extract and sourdough starter. Whisk together until well combined.

Pour the wet ingredients into the bowl with the dry ingredients and using a spatula, gently mix all of the wet and dry ingredients together.This is a thick brownie mixture - that’s ok, it’s meant to be like this.

Place the sourdough brownie mixture into your prepared pan and bake for 35 minutes at 160C/320F. Because this is a thick mixture, you might need to push the mixture out to the edges of the pan before placing it in the oven.

Check the sourdough brownies at 35 minutes by inserting a tooth pick - you want it to come out wet still but they should be crackly and baked on top.

Remove from the oven and allow to cool for around an hour before preparing the ganache topping.

To make the ganache, place the semi sweet chocolate chips and heavy whipping cream into a microwave proof jug and microwave for around 1 minute and 30 seconds. Carefully remove from the microwave and whisk together until it forms a glossy ganache.

Pour over the sourdough cosmic brownies and top with mini m&ms or sprinkles. Set in the fridge for 2 hours before slicing.