Cut the broccoli head into small florets and put in boiling water for 5 min.
In this time mix the cream with the almonds, 50 g of the cheese, a pinch of nutmeg, some freshly ground pepper and a pinch of salt. In a small bowl mix the flour with 3-4 spoons of water of water. Start with just one spoon of water and continue adding water spoon by spoon until smooth and then add to the cream.
When the potatoes are cooked cut in slices and put in the casserole and add the broccoli. Pour the cream and cheese mix on top and put in the oven for 20-25 minutes.
Top up the gratin with the last 50 g of cheese and bake until cheese is melted and has a light golden brown color.