I went to the produce section of my grocery store and picked up a tube of pureed Basil. I was hesitant the first time I tried it, but it tastes the same as the fresh stuff. Plus, for the amount you get, it's a lot cheaper than those individual packs. Of course, if you want to use fresh Basil, you can. Just use a food precessor or blender and puree the leaves with just enough water or olive oil to form a paste.
Lay out a sheet of plastic wrap. Squeeze the Basil paste into a line about an inch wide, leaving about 2 inches on either end of the line. If you pureed your own Basil, you can use a piping bag or a plastic zip-top bag with the corner snipped off to pipe the paste.
Fold the plastic wrap in half and roll the Basil into a log. (Sort of like a jelly roll) Make sure it's tight- this is crucial for even portioning, and so it doesn't squeeze out all over the place!
Twist the ends of the plastic wrap, and tie each into a knot. Now, take the entire log, and roll it in another sheet of plastic wrap, and twist and tie the ends again.
Place the roll in the freezer until completely frozen.
Place the slices into a zip top bag and store in the freezer. Now, next time you're making pizza sauce or soup, you can grab one or two slices of the Basil and pop them straight into the pan- no chopping required!