1. If you like, chill two cocktail glasses. Fill the glasses with ice. Divide 4 tablespoons of the syrup between 2 ice-filled glasses. Divide the gin among the glasses and top each with tonic water to taste. Add more blueberry syrup if you want a bit more berry flavor and color. Finish with the garnish of your choice!
2. For an alcohol-free version, simply use your favorite alcohol-free substitute. I like to use the brand Seedlip. Both their Seedlip Garden and Seedlip Notas de Agave are good choices for an alcohol-free substitute.

For the Blueberry Syrup

1. In a small pot, combine the berries, water, and sugar.
2. Bring the mixture to a boil, then reduce the heat and simmer the mixture for 7 to 10 minutes to reduce it slightly. Use the back of a spoon to mash the blueberries as they soften.
3. Remove from the heat and stir in the vanilla extract. Allow the mixture to cool for about 15 minutes.
4. Place the mixture into a blender and pulse to smooth it out. The mixture will be fairly smooth but may have a few berry pieces still in it. It’s your choice if you would like to process it through a strainer or enjoy it as is.
5. You can use the simple syrup immediately or once completely cooled, store it in the refrigerator for up to 2 weeks.