Preheat the oven to 375?F.
Fill a large pot three-quarters full with water and add 1 teaspoon of the salt. Bring to a boil over high heat. Add the cauliflower and cook until just tender, 8 to 10 minutes. Using a slotted spoon, transfer the cauliflower to a colander. Rinse under cold running water until cool. Drain well.
Add the broccoli to the boiling water. Cook until just tender, about 5 minutes. Drain the broccoli in a colander. Rinse under cold running water to cool. Drain well.
Butter a 15 x 10-inch baking dish (or 2 smaller dishes) with 2 teaspoons of the butter. Arrange the cauliflower evenly in the dish, then arrange the broccoli on top.
Melt the remaining 8 tablespoons butter in a heavy medium saucepan over medium heat. Whisk in the flour and cook, whisking, until the roux is a blond color, about 3 minutes. Add the remaining 2 teaspoons salt and the cayenne. Gradually whisk in the milk and whisk constantly until the mixture boils and thickens, about 4 minutes. Whisk in the cheese until it melts.
Pour the cheese sauce over the cauliflower and broccoli, and gently rap the dish on the countertop to remove any air bubbles.
Combine the bread crumbs, Essence, and olive oil in a small bowl, mixing well. Spoon the mixture evenly over the top of the vegetables.
Bake until golden brown, about 30 minutes. Serve hot.
Yield: 6 to 8 servings