Spread the panko into a 9-by-13-inch metal pan and bake until lightly toasted, about 2 minutes. Remove the panko from the oven and add to the bowl with the broccoli mixture. Toss to combine. Return the mixture to the cake pan, place in the oven, and roast just until the broccoli is tender, 8 to 10 more minutes. Remove from the oven, toss with the cheese and serve immediately.