Heat oven to 350°F. Coat 2-1/2-quart shallow baking dish with nonstick cooking spray.
Cook broccoli in large pot boiling salted water 8 minutes, until just crisp-tender. Drain; cool under running cold water. Blot dry.
Place half the broccoli in prepared baking dish. Sprinkle half of the Cheddar, Parmesan and pepper over top. Repeat, using the remaining broccoli, Cheddar, Parmesan and pepper. (Can be made ahead up to this point and refrigerated.)
Bake in 350°F oven 20 minutes (or longer if refrigerated), until heated through.