Step 1

Clean and wash the lemons. Cut off the top 1/4 of the lemons and shave a small slice off the bottom so it stands easily.

Step 2

Using a grapefruit knife, cut out the flesh of the lemon and place in a strainer set over a bowl. Be careful not to cut through the bottom. Stand the lemons on a cookie sheet and place in the freezer and freeze until solid.

Step 3

Press the flesh of the lemons through the strainer to extract all of the juice. You should end up with about 1 to 1 1/2 cups of lemon juice. Add the water to the lemon juice. Stir in sugar, a tablespoon at a time, until the mixture is of desired sweetness. Add the thyme and limoncello and let sit for 15 minutes.

Step 4

Strain the mixture into a roasting pan or baking dish. The dish should be large enough so the liquid is not more than 1-inch deep. Freeze the mixture for 1 hour. Remove from the freezer and scrape with 2 forks to break up ice. Return to the freezer and freeze until solid, about 2 to 3 hours, scraping with forks every hour or so.

Step 5

When the granite is frozen, scoop it into the frozen lemon shells and serve immediately.