1. Peel lemons with a sharp vegetable peeler, taking only the zest (top layer) and avoiding any white pith. Put rosemary in a 1-gal. glass or ceramic container with a tight seal. Add zest to jar.
2. Pour 750 ml. vodka over rosemary and zest; seal container. Let sit undisturbed in a cool, dark place for 40 days.
3. In a saucepan, bring 5 cups water to a boil and add sugar. Cook, stirring, until sugar has dissolved. Let sugar syrup cool to room temperature, about 1 hour.
4. Pour syrup and remaining 750 ml. vodka over lemon-vodka mixture, stir, and seal container. Let sit in a cool, dark place for another 40 days.
5. Pour limoncello through cheesecloth into a large spouted pitcher and divide among gift bottles.
Note: Nutritional analysis is per ounce.
Either Meyer or Eureka lemons work in this recipe (the fragrant Meyer is especially good, though). To speed up the process, shorten the infusing time in steps 2 and 4 to 1 week each, and you'll have a fine although less intense liqueur. Limoncello keeps indefinitely in the freezer.