Preheat oven to 170°C or fan forced.

Grease or line a 20 x 30cm rectangle baking tray and set aside.

Melt the chocolate and butter in a heatproof bowl set over (not in) a pan of simmering water. Stir to combine, then remove from the heat and allow to cool slightly.

If you have an induction cooktop, you can do the above step directly in the saucepan (without the need for the simmering water pot underneath) but do so on a low heat and stir often.

Add the sugar to the melted chocolate & butter and stir until combined.

Add the eggs one at a time, followed by the vanilla. Stir.

Add the flour and salt and then whisk hard for at least 1 minute. It is absolutely essential that the batter is whisked hard, by hand, for the full minute. You want to keep whisking until the mixture starts to come away from the sides of the bowl and is super glossy. This is what makes a good blondie to be a great one.

Add the cacao nibs (if using) and stir gently to combine.

Scrap the mixture into the prepared tin. Gently level the top with a spatula.

Dollop small amounts (randomly) of the dulce de leche.

Sprinkle over a tiny amount of extra salt.

Bake for approximately 30-35 minutes. The top should only just set with the edges more set than the middle. The middle, ideally, should have a gooey centre.

Set aside to cool.

Do not slice until completely cool or you will end up with a gooey mess. Keeps well in an airtight container for up to 4 days. This brownie freezes beautifully too.