How to Make Broccoli Gratin
- Place broccoli in a steamer over boiling water. Steam for 10 minutes. Place broccoli in a lightly greased 13x9 inch baking dish.
- Melt butter in a saucepan over medium heat; whisk in flour until smooth. Cook 1 minute until and whisk constantly, until bubbly.
- Stir in mustard and next 3 inredients.
- Pour sauce over broccli; sprinkle with cheese. Broil until lightly browned. Serve immediately.