Cauliflower Gratin with Mornay Sauce

Ingredients

For the Mornay sauce:

• 2
  
  tablespoons butter
  
• 2
  
  tablespoons flour
  
• 1 1/2
  
  cups half-and-half
  
• 2
  
  ounces fresh mozzarella, cut into small pieces
  
• 1
  
  teaspoon salt
  
• 1
  
  pinch nutmeg
  
• 1
  
  egg yolk
  
• 1/3
  
  cup heavy cream
  
• 1/2
  
  cup grated Parmesan
  
• 1/2
  
  teaspoon freshly ground black pepper
  

For the cauliflower gratin:

• 2 1/2
  
  pounds cauliflower, cored and cut into 1-inch pieces
  
• 1/3
  
  cup hazelnuts, chopped
  
• 1/4
  
  cup grated Parmesan
  

Directions

1. First, make the Mornay sauce: Melt butter in a small pot over medium heat, then add flour and whisk.
2. Add in half-and-half, whisking constantly, until it just starts to boil. Stir in mozzarella and continue to whisk until melted and the sauce starts to thicken, about 3 minutes. Add salt and nutmeg.
3. Remove sauce from heat and let cool for 10 minutes. Whisk in egg yolk, heavy cream, Parmesan, and pepper. Set aside.
4. Preheat oven to 400º F.
5. Begin to arrange the gratin: Bring a pot of salted water to a boil. Add cauliflower florets, cover with lid, and cook for 6 minutes.
6. Drain the cauliflower and run them under cold water. Transfer florets to a paper towel-lined plate to dry.
7. Coat the bottom of a 10-inch square or similar baking dish with a thin layer of Mornay sauce. Arrange cauliflower florets on top of sauce and top with the remaining Mornay.
8. Sprinkle chopped hazelnuts and Parmesan on top.
9. Bake for about 15 minutes. Turn broiler onto high and cook until top starts to brown, about 5 minutes.