Wash the cherries, remove the stalks, halve and pit them.
Measure out all the ingredients except the vanilla extract.
Mince the rosemary.
Place the cherries in wide pan, with sides tall enough to hold the liquid when it bubbles and froths.
Add a smidgeon of salt (less than a pinch), add sugar, orange zest, cinnamon, minced rosemary and the orange juice.
Stir and bring the mixture to a boil, stirring so that the sugar dissolves.
Keep on a simmer on low heat for 5 minutes, stirring occasionally. Sugar syrup heats to very high temperatures, so handle the pan with care.
Drain
Remove from the stove and drain the cherries into a clean bowl.
Replace the pan with the syrup on the stove, and boil on low heat for about 10 minutes or till the syrup thickens, stirring frequently.
Add a drop of vanilla extract, stir and add back the cherries.
Boil for another 5 minutes and remove from the stove.
Allow to cool and transfer to a container for storing till required to be used.