Rosemary Grapefruit Milk Punch

For the rosemary simple syrup:

• 1 cup water
  
• 1 cup sugar
  
• 1 1/2 tablespoons dried rosemary
  

For the milk punch and cocktail:

• 3 cups brewed green tea, cooled
  
• 3 cups fresh lemon juice
  
• 3 cups fresh grapefruit juice
  
• 1 cup rosemary simple syrup
  
• 1 cup gin
  
• 3 cups whole milk
  
• Additional gin, to make each cocktail
  

1. Make the rosemary simple syrup: In a small saucepan over medium-low heat, mix the water, sugar, and dried rosemary together. Heat and stir just until the sugar is dissolved, then remove from the heat. Let sit for 20 minutes before straining into a jar. Let cool completely before using.
2. Make the milk punch: Combine cooled tea, lemon juice, grapefruit juice, rosemary simple syrup, and gin in a large pitcher or very large bowl.
3. In a medium sauce pan over medium heat, bring the milk to a bare simmer. Immediately pour the milk into the gin mixture. (The milk will curdle right away). Cover and chill at least 1 hour and up to 24 hours.
4. Strain the mixture through a fine-mesh sieve lined with cheesecloth into a large bowl. Cover and chill until cold. (Any remaining curds should settle at the bottom of the bowl).
5. Carefully ladle the clarified punch into a clean pitcher, leaving any remaining curds behind. Chill until ready to serve. (This punch base can be made 1 week ahead.)
6. Make the cocktails: For each cocktail, combine 1 1/2 ounces gin and 2 ounces milk punch base in a cocktail shaker and fill shaker with ice. Shake for about 30 seconds, and strain into a rocks glass with one large ice cube.