Step 1

Preheat the oven to 175 C. Line an 8-inch square baking pan with non-stick baking paper, leaving a little overhang. If using a 'not non-stick baking paper', you will need to lightly grease it.

Step 2

Add the butter, chocolate and cocoa to a heat-proof bowl placed over a pot of simmering water, taking care that the bowl isn't touching the water. Stir often till melted and smooth. If a few small lumps of chocolate remain, take the bowl off the heat and stir to melt them completely. Set aside to cool for a few minutes.

Step 3

In a mixing bowl, combine the sugar and hot water, whisking till the sugar has dissolved (a balloon whisk is useful in this recipe).

Step 4

Stir in the vanilla extract, then pour in the melted chocolate mixture. At this stage both liquids will be warm so they'll be easy to stir together with a spoon or whisk, until you have a smooth mixture.

Step 5

Now stir in the yoghurt until incorporated, then sift in the flour, salt and cornstarch.

Step 6

Fold gently to combine into a smooth, thick batter, using the whisk to break up any flour lumps. Spread the batter into the prepared pan, smoothening the top and making sure it's even all over.

Step 7

Bake for 25 to 30 minutes, until you see a crust has formed on top and a toothpick poked in the center comes out with moist crumbs but no wet batter. If you bake it till the toothpick is completely clean, the brownies will be dry and over-baked. Some readers have said the brownies crumbled along the sides and because ovens do vary, you can also start checking for doneness at 20 mins to reduce the chance of over baking.

Step 8

Allow the brownies to cool completely at room temperature before lifting them out of the pan using the paper overhang and slice into 16 equal pieces, wiping the knife down after every cut to get neat pieces. I actually recommend slicing these on day two if you can wait, because the texture improves. When freshly sliced, the center pieces could feel slightly greasy but I noticed that by day two they looked and tasted perfect. Chilling the brownies for about 30 minutes before slicing also helps with neater pieces.

Step 9

Brownies can be stored at room temperature in an airtight tin for 4 to 5 days, or in the fridge for about 10 days where they will be extra fudgy. Happy baking!