Step by step recipe:

1. 10 min.
   Preheat the oven to 390°F (200°C).
   
   Spread 100 g rolled oats in a thin, even layer over a sheet of cooking parchment laid on a baking sheet.
   
   Toast in the oven for 10 minutes.
2. 5 min.
   At the end of this time (do watch for the colour and don't let them get too brown), take them out of the oven and leave to cool.
   
   When cold, blend the toasted oats to a floury consistency.
3. 3 min.
   Use a whisk to mix the oats into 150 g flour and 200 g caster sugar.
4. 3 min.
   Put into a food-processor bowl, then add 4 eggs, 250 g butter and 1 pinch salt.
5. 5 min.
   Mix well.
6. 
   Stop beating once the mixture appears smooth and evenly mixed.
7. 2 min.
   Put the mixture into a loaf tin or mould.
8. 40 min.
   Bake for about 40 minutes.
   
   Check if the cake is cooked after 30 minutes.
9. 
   Leave to cool on a wire rack before eating.