In a small saucepan, combine 1 cup of granulated sugar, ½ cup of crushed mint leaves, and 1 cup of water. Heat over medium heat, stirring continuously until the sugar has completely dissolved, about 3-5 minutes. Once the mixture is clear, remove it from heat and let it cool completely.

In a mixing bowl, add 1½ cups of fresh blackberries along with 2 teaspoons of sugar and ¼ cup of freshly squeezed lime juice. Using a fork or a potato masher, gently mash the blackberries until well combined, leaving a few chunky bits for texture.

Grab a tall glass and layer a few tablespoons of the blackberry mixture at the bottom. Pour in approximately ¼ cup of the mint simple syrup, allowing it to blend with the berries. Then, carefully add about 2½ cups of sparkling water.

Garnish with fresh blackberries, lime slices, and additional mint leaves. Fill the glass with ice before serving.