Measure into a bowl your nutella and add the eggs (mine were large) mix well.
Add flour and mix well. Pour into a lined slice tray (28x18cm).
In a preheated 170-175*C oven, bake for approx 12-15 minutes or until just set in the middle.
Cool mostly in the tray and them turn out (use the double cake cooler method is easiest). Cool and cut into squares.
Notes
Could you use other chocolate nut spreads, I don't see why not.This freezes well and takes 5 mins to defrost on the bench top.Next time I might try 1/4 cup flour with 1/4 cup of hazelnut meal to see what happens.