Wash the broccoli and divide into florets, chop the stems and blanch in salted water for 3 minutes. Place in a greased baking dish and sprinkle with 100 g grated cheese.
Bake in a hot oven at 180 °C top/bottom heat for 15 minutes.
Meanwhile, mix sour cream with vegetable broth and flour until smooth, bring to a boil in a saucepan while stirring and simmer for a few minutes, season with salt and pepper.
Stir in the remaining cheese and stop cooking, finish with chopped parsley. Arrange the broccoli on 4 plates and nap with the sauce, sprinkle with parsley if desired.