For the Rosemary Simple Syrup:

1. In a medium sized saucepan bring water to a boil. Stir in sugar. Once the sugar has dissolved add in rosemary and remove from heat.
2. Let stand for an hour, remove rosemary and let mixture cool completely. When not using the mixture keep stored in the refrigerator. 

For the Pear Puree:

1. Add ingredients to a food processor or blender and blend till smooth.
2. Strain through a mesh strainer and store in the refrigerator. 

For the Rosemary Pear Cocktail:

1. In a cocktail shaker add ice, pear puree, rosemary simple syrup and vodka. Shake until cold.
2. Pour into an ice filled tall cocktail glass. Fill to the top with sparkling water.