Clean broccoli, wash it. Peel and slice thick stems. Boil up salted water. Cook broccoli in it for about 10 minutes. Bring 750 ml water and 1 teaspoon salt to the boil. Remove the pot from the heat and add 1/4 litre cold milk.
Stir in the mashed potatoes. Allow to swell for approx. 1 minute and stir again. Melt butter and sweat flour in it. Deglaze with 1/8 litre milk and stock. Add the cheese while stirring. Season to taste with salt and pepper.
Put the puree and broccoli in a greased casserole dish. Spread the sauce over it, sprinkle with almond flakes. Bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 10 minutes.