Cauliflower and Brussels Sprout Gratin With Pine Nut-Breadcrumb

Ingredients:
1 1/2 lbs fresh Brussels sprouts, trimmed, quartered lengthwise through core
1 1/2 lbs heads cauliflower, trimmed, cut into small florets
2 3/4 cups heavy whipping cream
1/2 cup chopped shallot
1 tablespoon chopped fresh sage
1 1/2 tablespoons olive oil
1/2 cup pine nuts, lightly toasted
1/2 cup plain breadcrumbs
2 tablespoons chopped fresh Italian parsley
3 cups grated parmesan cheese, divided

Directions:
Fill large bowl with ice and cold water.
Cook brussels sprouts in large pot of generously salted boiling water, 2 minutes.
Add cauliflower to same pot; cook until vegetables are crisp-tender, about 3 minutes longer. Drain. Transfer vegetables to bowl of ice water to cool. Drain well.
Combine cream, shallots, and sage in large saucepan.
Bring to boil.
Reduce heath; simmer until mixture is reduced to 2 1/2 cups, about 10 minutes.
Season with salt.
Remove from heat. Cool slightly.
Heat oil in large nonstick skillet over medium heat.
Add breadcrumbs; stir until beginning to brown, about 2 minutes.
Transfer to bowl; cool.
Stir in pine nuts and parsley.
Season with salt and pepper.
Butter 13x9x2-inch glass baking dish; arrange half of vegetables in dish.
Sprinkle with salt and pepper, then 1 1/2 cups Parmesan.
Arrange remaining vegetables evenly over, then sprinkle with remaining 1/12 cups Parmesan. Pour cream mixture evenly over.
(DO AHEAD Breadcrumb topping and gratin can be made 1 day ahead. Cover separately and chill. Bring to room temperature before continuing.)
Preheat oven to 375.
Cover gartin with foil.
Bake covered 40 minutes.
Uncover; sprinkle breadcrumb topping over and bake uncovered 15 minutes longer.