Preheat the oven to 180ºC. Line a 9 inch (23cm) square tin with baking paper. *See notes

In a medium bowl add the sugar and eggs to a bowl and mix them well.

Melt the butter in a small saucepan or in the microwave, set aside to cool for a few minutes. Once cooled gently, pour the butter into the eggs and sugar.

Whisk them well.

Weigh the flour into the bowl and mix it into the eggs and sugar mixture. The mix will get really thick. Like really, really thick! *See notes

Once the batter is very well mixed, Sprinkle with some sea salt if you've got it!

Pour everything into a square tin and smooth the surface so it’s even. Drop large spoonfuls of Nutella on to the top of the blondie and use a toothpick or knife to swirl the Nutella through the batter. Bake in a preheated oven for about 25- 30 minutes.

When the blondies are done, they’ll be set when the pan is wiggled gently and the top will have a crust with a slight crackle look to it.

You can insert a knife into the blondies and if it comes out clean remove the blondies from the oven. Let them cool completely in the pan. Once cooled, cut into 9 equal squares.