14 Mar Cauliflower – Broccoli Gratin
1 broccoli crown, trimmed and cut into 1-inch florets (about 4 cups)
1/2 head cauliflower, trimmed and cut into 1-inch florets (about 4 cups)
2-3 Tbsp extra-virgin olive oil, divided
1 medium onion, thinly sliced
3 Tbsp all-purpose flour
3/4 tsp salt
1/4 tsp white or black pepper
2 1/2 cups low-fat milk
1 1/2 cups fresh whole-wheat breadcrumbs (see tips) or 1/2 cup shredded or crumbled cheese
Position racks in upper and lower third of oven; preheat to 425 degrees F.
Toss broccoli and cauliflower in a large bowl with 1 Tbsp oil until well coated. Divide between 2 baking sheets and spread in an even layer. Roast the vegetables, stirring once and rotating the pans top to bottom about halfway through, until tender and beginning to brown, 20-25 minutes.
Meanwhile, heat 1 Tbsp oil in a large saucepan over medium heat. Add onion and cook, stirring frequently, until very soft and golden brown, 5-8 minutes. Add flour, salt, and pepper; cook, stirring for 1 minute more. Add milk and continue to stir, scraping up any browned bits. Cook, stirring, until the sauce bubbles and thickens enough to coat the back of the spoon, about 4 minutes. Remove from the heat. (See tips)
When the vegetables are done, remove from the oven. Preheat the broiler. Transfer half the vegetables to a 2-quart, broiler-safe baking dish. Spread half the sauce over the vegetables. Add the remaining vegetables and top with the remaining sauce.
Combine breadcrumbs and the remaining 1 Tbsp oil in a small bowl (skip this step if you are topping with cheese).
Sprinkle the breadcrumb mixture (or cheese) over the gratin. Place under the broiler and broil, watching closely, until the gratin is bubbling and beginning to brown on top, 1-5 minutes, depending on your brother.
Let stand for 10 minutes before serving.