Brussels Sprouts Gratin

• 11 tablespoons butter, plus some for greasing the pan
• 1 large vidalia onion, cut into 1/4 inch dice (about 2 1/2 cups)
• 8 garlic cloves, chopped
• salt
• 4 cups heavy cream
• 2 lbs Brussels sprouts
• 3 tablespoons all-purpose flour
• 1 tablespoon mustard powder
• 14 teaspoon fresh grated nutmeg
• 1 cup panko breadcrumbs
• 1 12 ounces parmesan cheese, grated (about 1 cup)
• 1 large lemon

1. Preheat oven to 375F Use a little butter to grease a 2 quart casserole dish.
2. Melt 3 tablespoons butter in a 4 quart dutch oven over medium heat.
3. Add the onions, garlic, and a pinch of salt and cook until soft, about 15 minutes.
4. Add the cream and bring to a simmer.
5. Turn the heat to low and cook until the cream is slightly thickened, about 5 minutes.
6. Meanwhile, thinly slice the brussels sprouts crosswise on a mandolin, slicing just until you get to the hard core.
7. Melt another 2 tablespoons of the butter in a small skillet over medium heat.
8. Stir in the flour and cook, stirring constantly, just until it begins to smell toasty, about 2 minutes.
9. Mix the mustard with 1 tablespoon of water to make a thin paste.
10. Whisk 2 tablespoons of the flour mixture into the onions along with the mustard paste, nutmeg, and 2 teaspoons salt; crank the heat up to medium and continue whisking until the mixture comes to a simmer and thickens, about 2 minutes.
11. Cut heat to low and cook until the sauce loses any floury taste, about 10 minutes.
12. Fit a food processor with the metal blade, and add the panko, Parmesan, 1 teaspoon salt, 1/2 teaspoon lemon zest, and the remaining 6 tablespoons butter.
13. Process to a crumbly paste.
14. Spread the crumb mixture on a sheet of parchment paper and top with another sheet.
15. Use a rolling pin to roll the crust to fit the top of the casserole.
16. Carefully pour the onion sauce in a blender and blend until smooth.
17. Add the remaining zest from the lemon, all of the lemon's juice, and 1 teaspoon salt.
18. Blend again until smooth.
19. Pour the sauce back into the pot and fold in the sliced brussels sprouts.
20. Bring the mixture to a gentle simmer and cook until the sprouts are wilted, about 5 minutes.
21. Spoon the mixture into the prepared casserole and invert the prepared crust over the brussels sprouts.
22. Bake until golden brown and bubbly, about 40 minutes.

butter, vidalia onion, garlic, salt, heavy cream, brussels, allpurpose, mustard powder, nutmeg, breadcrumbs, parmesan cheese, lemon

Taken from www.food.com/recipe/brussels-sprouts-gratin-490515 (may not work)