Preheat the oven to 450 degrees. Spray a 9 x 13 baking dish with cooking spray.
Place the broccoli and cauliflower in the baking dish.
In a medium bowl combine the panko, melted butter, oregano, paprika, and cayenne. Mix well and set aside.
Sprinkle the broccoli and cauliflower with salt and pepper. Sprinkle the Velveeta cheese pieces evenly over top of the vegetables. Sprinkle with cheddar cheese. Carefully pour the milk over top of the broccoli and cauliflower. Mix well with a spoon.
Sprinkle the breadcrumb mixture evenly over the top of the broccoli and cauliflower.
Cover the dish with foil and bake for 20 minutes. Remove the foil and continue baking for 10 minutes.
Serve hot.