All you need is:
1 cup (280g) Nutella
2 Eggs
10 tbsp of flour (62g)
Put it all in a bowl and mix it together.
I put mine on some grease proof paper and then put them in the oven for around 30mins. The oven temperature was between gas mark 4 & 5 (350F or 180C)
Here are some photos of my finished brownies.