Cauliflower and Brussels Sprouts Gratin

Cut cauliflower into large florets. In large pot of boiling water, cover and cook cauliflower until tender-crisp, about 5 minutes. Remove with slotted spoon and chill under cold water; drain well.

In same pot, cover and cook brussels sprouts until tender-crisp, about 7 minutes. Drain and chill under cold water; drain well. Wrap cauliflower in kitchen towel and gently press out excess water; repeat with sprouts. (Make-ahead: Wrap in plastic wrap and refrigerate for up to 24 hours.)

In saucepan, melt butter over medium heat; whisk in flour, salt, pepper and nutmeg; reduce heat and cook, stirring, for 1 minute. Gradually whisk in milk, stirring, until thickened, about 5 minutes. Remove from heat. Stir in cheese. (Make-ahead: Pour into airtight container; place plastic wrap directly on surface and let cool. Refrigerate in airtight container for up to 24 hours. Reheat, stirring, over low heat before continuing.)

Spread cauliflower and brussels sprouts in greased 13- x 9-inch (3 L) casserole. Pour sauce over top; sprinkle with bread crumbs. (Make-ahead: Cover with plastic wrap and refrigerate for up to 8 hours.) Bake in 400°F (200°C) oven until bubbly, about 25 minutes. Broil until crumbs are golden, 3 minutes.