Preheat the oven to 425° F. Spread the broccoli, cauliflower and Brussels sprouts out on a sheet pan in one layer. Drizzle with 3 tablespoons olive oil and season with garlic powder, onion powder, fennel seed, crushed red pepper, oregano, turmeric, curry powder and a shake of salt and pepper. Roast for 25 minutes, then remove from the oven.

In the meantime, heat a sauté pan over medium-high heat. Melt 2 tablespoons of butter in the pan, then add in the leeks and garlic clove. Sauté, stirring occasionally, for 10 minutes until softened. Remove from the heat.

In a small bowl, melt the remaining 2 tablespoons of butter in the microwave, then mix in the breadcrumbs, Italian seasoning, and a pinch of salt and pepper. Add in 1/4 cup of the shredded Cabot cheese into the breadcrumb topping.

Lower the oven to 400° F, then start to build the gratin in a casserole dish. Layer half the roasted vegetables, then half the leeks, then half the shredded cheese and half the breadcrumbs. Repeat with the remaining ingredients. Bake for 20 minutes until gratin is bubbly and the top is lightly browned.

Let cool for a couple minutes, then serve!