Broccoli Kale Gratin

1 bunch broccoli, chopped (peel the stems and chop those up too)
1 bunch kale, leaves stripped, chopped
2 cups milk, heated
¼ cup butter
¼ cup flour
1 teaspoon onion powder
½ cup grated Parmesan cheese
sea salt and white pepper to taste
1 cup breadcrumbs
2 tablespoons butter, melted

1. Heat oven to 400°F. Bring a large pot of lightly salted water to a boil and add the kale and broccoli. Cook for about 5 minutes until tender-crisp. Drain, rinse under cold water, and set aside. While kale and broccoli are cooking, stir together the bread crumbs and melted butter.
2. Melt the 1/4 cup butter in a heavy-bottomed saucepan. Stir in the flour and cook, stirring constantly about 2 minutes. Whisk in the hot milk and onion powder, continuing to stir as the sauce thickens. Bring to a boil. Add salt and pepper to taste, lower the heat, and cook, stirring for 2 minutes more. Stir in the parmesan cheese. Remove from heat.
3. Layer the broccoli and kale in a greased casserole dish. Pour the sauce evenly over the veggies and sprinkle with the buttered bread crumbs. Bake for 30 minutes, until golden-brown and bubbly. If desired, place under a broiler set to high for 1-2 minutes to create more of a crusted top.