Add frozen cherries and vanilla to a medium saucepan and heat over medium/high heat just until boiling and all cherries are defrosted
Mix arrowroot powder in a small bowl with 2 Tbs water until it is dissolved
Add arrowroot mixture to just boiling cherries
Stir sauce until thickened. This should happen very quickly if the cherries are boiling.
Remove from heat once desired thickness is reached and serve
