head (2 lb) cauliflower, cut into large florets
lb Brussels sprouts, trimmed and quartered lengthwise SAVE $
tablespoons all-purpose flour
cup hot milk
cup hot heavy whipping cream
cup shredded Gruyère cheese
cup shredded Parmesan cheese
teaspoons kosher salt
teaspoon fresh ground black pepper
teaspoon garlic powder
Pinch grated nutmeg
cup plain bread crumbs
Heat oven to 375°F. Spray bottom and sides of 2 1/2- to 3-quart baking dish with cooking spray.
In 5- to 6-quart saucepan, cook cauliflower florets in boiling salted water 3 to 4 minutes or until tender but still firm. Use slotted spoon to transfer cauliflower to colander to drain. Add Brussels sprouts to boiling water; cook 3 to 4 minutes or until tender but still firm. Drain.
In 4-quart saucepan, melt 2 tablespoons of the butter over medium-low heat. Add flour; cook 2 minutes, stirring constantly with whisk. Slowly pour hot milk and hot whipping cream into butter-flour mixture; beat with whisk until smooth. Increase heat, and heat to boiling, beating constantly, 1 to 3 minutes or until thickened. Remove from heat. Stir in shredded Gruyère cheese and 1/3 cup of the shredded Parmesan cheese until smooth. Stir in salt, 1/4 teaspoon of the pepper, the garlic powder and nutmeg until combined.
Add drained cauliflower and Brussels sprouts to sauce. Gently stir to coat. Pour into baking dish. In small microwavable bowl, heat remaining 4 tablespoons butter uncovered on High 30 seconds or until melted. Stir in bread crumbs, remaining 1/3 cup Parmesan cheese and remaining 1/4 teaspoon pepper to combine. Sprinkle evenly on top.
Bake 30 to 35 minutes or until top is golden brown and mixture is bubbly. Let stand 10 minutes before serving.