Purple Rain (a Cocktail to Honor Prince)

For the Blackberry Lavender Simple Syrup

• Large handful of blackberries
• 1 tbsp lavender
• 1 c water
• 1 c granulated white sugar

For the Cocktail

• 0.5 oz blackberry-lavender simple syrup
• 2-3 blackberries
• 2-3 purple grapes
• 3 oz low-sugar tonic water
• 2 oz Empress 1908 Gin
  
• Blackberries and purple grapes for garnish

1. To make the simple syrup, combine the blackberries and lavender with the water and sugar in a saucepan. Bring to a boil, and then reduce to a low boil. Use a fork to carefully smash each berry so that it releases its colorful juice. Boil until the mixture has reduced significantly and turned a dark pink-purple color. It should be thick enough to coat the back of a spoon; keep an eye on it and don't let it go too far.
2. Strain the simple syrup through a fine-mesh sieve to remove all of the berry seeds and bits of lavender.
3. Put the simple syrup in a jar or container and chill it for at least several hours.
4. Add the simple syrup to the bottom of a highball glass.
5. Add some large ice cubes into the glass, as well as blackberries and purple grapes interspersed throughout the ice.
6. Pour a few oz of tonic water over the ice.
7. Gently float the gin on top of the tonic, allowing the layers to mix partially but not completely.
8. Garnish with a few additional blackberries and grapes.
   
9. Serve with a straw (ideally a purple one!) for mixing and/or for tasting the different layers separately.