The closest spread to peanut butter I've found in terms of flavor and texture is sunflower seed butter. It's also relatively easy to find; I've seen it in large chain grocery stores right next to the peanut butter.
A curmudgeon with years of practice. The bubbles in boiling water are steam or vaporized water. The bubbles initially do not reach the surface of the billing fluid as the colder water away from the hot bottom cools the steam turning it back to liquid. WHen all the water is at 100oC the bubbles reach the top.
After big bubbles (not small ones at the sides of the pot) appear in the center of the pot -- they should roll over each other, thus the name -- set a timer for one minute. Turn off the heat after one minute. (You can also boil water in the microwave, but it's harder to see the bubbles and know when to start timing.)