2 cups unsweetened & unflavored almond milk or other milk of choice, divided
3 tablespoons butter (dairy-free can be used)
3 tablespoons cornstarch
1 cup shredded Gruyere or cheddar cheese, optional (can omit if dairy-free)
bread crumbs, for crunchy topping (Optional. Use gluten-free breadcrumbs if needed)
Preheat oven to 450ºF. Place broccoli and cauliflower into a 9×13-inch(ish) oven-safe baking dish. Cut or break any large florets into smaller pieces. Sprinkle with salt and pepper and place into the oven to dry roast for 15 minutes, while you make the béchamel.
Meanwhile, heat 1 3/4 cup milk and butter in a saucepan over medium heat. Whisk together remaining 1/4 cup milk and cornstarch. When milk is heated, add the cornstarch slurry to the pot, stirring continuously until thickened. Reduce heat to low and if you’re adding cheese, add it in now, along with salt and pepper, to taste.
Remove broccoli and cauliflower from the oven and reduce heat to 350ºF.
Pour béchamel over the roasted veggies and top with bread crumbs. If you’re grain/gluten–free, you can omit the bread crumbs, use a gluten-free variation, or use a handful of grated parmesan cheese in its place.
Place back into the oven to bake until hot and bubbly, and top is lightly brown, about 30 minutes. Serve right away.