broccoli and cauliflower casserole

medium head of cauliflower

large broccoli crowns (1 pound)

plus 1 teaspoon extra-virgin olive oil, divided

large leek, white and pale green part only, sliced and washed

salt

all-purpose flour

fat-free milk (lactose-free if desired)

sharp lactose free cheddar, shredded (I used Cabot Alpine)

ground white pepper

panko, preferably whole-wheat

paprika

garlic powder