Make the Blueberry Rosemary Syrup:

In a small saucepan, combine blueberries, sugar, water, and rosemary sprigs.

Bring to a boil, then reduce heat and simmer for about 10 minutes until the blueberries have burst and the syrup has thickened slightly.

Remove from heat and let it steep until cooled. Strain the syrup through a fine mesh sieve, pressing on the solids to extract all the liquid. Discard solids and chill the syrup.

Assemble the Spritzer:

In a cocktail shaker, combine vodka, blueberry rosemary syrup, and lemon juice with ice.

Shake well until the mixture is well chilled.

Strain into a glass filled with ice.

Top off with sparkling water or club soda to your taste.

Gently stir to combine.

Garnish and Serve:

Garnish with fresh blueberries and a sprig of rosemary.

Serve immediately and enjoy the refreshing taste.