In a heavy-bottomed saucepan on stove top over medium heat, combine sugar, corn syrup and water. Insert a candy thermometer, stirring sugar until it reaches 320 F.
Remove from heat and pour into a microwaveable glass bowl, adding lavender , vanilla and food coloring.
Lay parchment paper down on your work space.
Dip your whisk into sugar mixture and hold it over bowl to let sugar mixture drip back into bowl for a second. Hold whisk above parchment paper and swing it back and forth so that thin strands of sugar fall onto paper. Repeat this a few more times, making a nice little nest of spun sugar (cotton candy).
Roll cotton candy onto a piece of paper that you've rolled into a long, thin cone or a long lollipop stick. Sprinkle with rosemary. If not eating right away, place cotton candy into a container that is airtight. If not, sugar will begin to melt.