4Mix broccoli, corn, onion and walnuts and place in pan.
5Beat remaining ingredients except cheese until smooth, 15 seconds, in blender on high, stopping blender frequently to scrape sides if necessary, or 1 minute with electric mixer on high and pour evenly into pan.
6Bake until knife inserted in center comes out clean, 23-25 minutes, and sprinkle with cheese.
7Bake until cheese is melted, 2-3 minutes longer.
8Cool 30 minutes and cut into triangles or squares.