Broccoli gratin

Name: Broccoli gratin
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Yield: 2 servings
Cuisine: European
Ingredients: 1 pinch of Black pepper; 1 Broccoli; ½ tsp of English mustard; 1 pinch of Fine sea salt; 70 gr of Grated mature cheddar cheese; 60 gr of Plain flour; 600 ml of Semi skimmed milk; 60 gr of Unsalted butter