Yes, you can use frozen broccoli, but it should be thoroughly thawed and drained. Fortunately, most frozen broccoli is bagged now instead of frozen into those neat little 4 x 6” boxes of old, which made for a good solid green block of ice. However, either type can be placed in a colander with a plate under it and allowed to thaw. Once the broccoli has thawed and drained, pat dry with paper towels or a clean, lint-free cotton cloth.