Soak the Lemons in a bowl of water with a 1/3 cup White Vinegar and 1 tbsp baking soda for 10 mins. Rinse well.
Peel the lemons, removing just the peel not getting any pith (the white part). Place the peels in a non-reactive glass container, pour the liter of grain alcohol over the peels and seal well. Make sure the container is sealed well or the alcohol will evaporate. Place in a cool, dark place for 2 weeks. Shake every few days. **KEEP THE BOTTLE OF THE GRAIN ALCOHOL FOR THE FINISHED PRODUCT**
After two weeks, the lemons have released their oils. Into a sauce pan, add milk, heavy cream and sugar and bring to a light simmer just long enough to melt the sugar. Turn the heat off and let it cool completely.
Using a fine mesh strainer, strain the lemon peels into a large bowl. Discard the peels. Add the cooled milk and cream mixture to the bowl and mix with alcohol.
Place a funnel into the swing top glass bottle. Slowly pour a liter into the bottle. Use the original grain alcohol bottle to pour the second liter in using a funnel.
Store in the freezer. This will last 6 months to a year. Its normal for the alcohol to separate from the cream, so shake well before serving.