Ingredients

• 9 ounces fresh blackberries (about 1 1/2 cups)
• 1 cup sugar
• 2 cups chilled dry gin
• 3/4 cup fresh lemon juice
• 2 cups chilled club soda
• Lemon wheels (for serving)

Instructions

1. Bring blackberries, sugar, and 1/2 cup water to a boil in a medium saucepan, stirring until sugar is dissolved. Reduce heat so that liquid is at a simmer and cook, stirring occasionally, until fruit is very soft, 20–25 minutes. Let blackberry syrup cool, then strain through a fine-mesh sieve into a large pitcher, pressing on fruit to extract as much liquid as you possibly can; discard solids.
2. Add gin and lemon juice to syrup in pitcher. Add ice to fill and stir until chilled, about 3 minutes.
3. Fill Collins glasses with ice cubes and divide cocktail among glasses. Top each with ¼ cup club soda and garnish with lemon wheels.