Char peach slices for a few minutes on both sides over a grill or grill pan at medium-high heat
Lightly bruise rosemary with a meat tenderizer mallet
Add all ingredients to a saucepan over medium-high heat, and stir to incorporate
When the mixture begins to boil, turn down the heat to a simmer
Breakup the peaches with a masher or fork
Simmer for 5-10 minutes, then fine mesh strain into an airtight container and bring to room temperature or cool for use in cocktails
Store in the refrigerator