After you use your beet greens, remove the tips and cut the beets into quarters or halves, depending on the size. Wrap one to one-one-half beets in each foil pouch and place on a parchment-lined sheet pan (the natural sugars in the beets seep out of the pouches on occasion and will burn an unlined pan). DO THIS ON A NIGHT YOU’VE HAD YOUR OVEN ON TO 350 OR ABOVE.
When you remove your first dish from the oven and turn the dial off, toss your beet pouches in. They will be done in the morning. Write yourself a note so you don’t forget to take the beets out. This technique will work with residual heat any time of day–takes about an hour or until your oven cools.
Unwrap, peel, and place golden beets in an ice water bath for a few minutes to set the color. Drain, then store the golden and red beets together in the refrigerator, placing the golden ones on the bottom so the red/purple color bleeds into them. Gorgeous, delicious, nutritious, and carbon neutral.
University of Maryland Medical School (discussion of betaine supplements)