It's the perfect way to add basil to soup and pasta sauce all winter. The flavor isn't quite as strong as fresh herbs, but certainly more flavorful than dried herbs. If you have leftover broth, you can also use broth instead of water, as suggested on The Kitchn.
I bought two different types of ice cube trays because I wasn't sure which type I would prefer for freezing herbs. First, I bought a cheap one ($1.39) at the grocery store, and the size is perfect.
However, the cubes are a little hard to get out but not nearly as difficult as the Amazon reviewers make it sound. I have since bought a second tray, in a different color, so I can remember which tray has basil and which has parsley while they're freezing.
The second type I tried is Tovolo Perfect Cube, which I ordered from Amazon for $5 each. The cubes are really easy to release, however the size is bigger than I would prefer. I do love the look of the 1oz square cubes though. The package says "add class to any drink or cocktail." :)
After filling each small tray with approximately 1 teaspoon of chopped basil, I added just enough water to cover the basil, but not quite to the top (it helps to have a slow water speed for this step).
Freeze the trays for a few hours, then add more water (just enough to bring the water level to the top of each indentation) to cover the basil that floated to the top.
This is just one easy way to add a little garden freshness to your recipes over the winter. I've tried parsley and basil so far, but will use Kalyn's method for the various types of thyme in my container garden.