1. Make the chamomile syrup: In a small bowl, combine the boiling water and chamomile tea. Steep for 5 minutes, then pour the mixture through a fine-mesh sieve lined with cheesecloth and set over a small saucepan (discard the tea solids). Add the sugar to the pan and heat over medium heat, stirring, until the sugar dissolves, about 2 minutes. Set the syrup aside to cool, then transfer to an airtight container and refrigerate to chill (the syrup can be refrigerated for up to one month).

2. Make the cocktail: In a cocktail shaker, add 6 raspberries and ½ ounce chilled chamomile syrup. Muddle thoroughly. Add the lemon juice and the gin and fill the shaker with ice. Cover and shake vigorously, then strain through a fine-mesh strainer and into an ice-filled Collins glass. Top with club soda and garnish with the 2 remaining raspberries.

½ cup of extra-ripe blueberries can be substituted for the raspberries.