EDIT: Sorry, the video is gone, but the text should still be helpful.
The hardest part of NG+ for me was the boss rush. Took me a lot of tries. Here's my video. Not pretty at times, but may be helpful.
You only get food every other boss. The other times there will be a bomb on the tray. But be sure to open the tray when it is a bomb or you won't get the food next time.
Also make sure you have the chalices filled with the red stuff.