Add the sugar and water to a small saucepan and bring the mixture to a boil. Once it boils, simmer for 5 minutes while stirring occasionally. Make sure all the sugar dissolves.
Skewer the marshmallows and toast them over the burner flame until brown.
Add the toasted marshmallows to the syrup and stir for 3 minutes. Ensure all marshmallows are dissolved.
Strain the mixture into a bowl and allow it to cool
Add in the vanilla extract and stir until thoroughly mixed
Store the syrup in an airtight bottle and store it in the fridge. It will last up to a month.
Notes
If you wish to achieve the best results, do not burn the marshmallows when toasting them. Ensure they are slightly toasted, as opposed to having black burned spots.