Preheat your oven to the broil setting.
Skewer the large marshmallow on the wooden skewer.
Place the marshmallow on a baking sheet and broil it in the oven until it turns golden brown. Keep an eye on it as marshmallows can quickly go from toasted to burnt.
In a cocktail shaker, combine the vanilla vodka, marshmallow-flavored liqueur, white chocolate liqueur, half-and-half, and simple syrup.
Fill the shaker with ice cubes and shake vigorously for about 20 seconds to chill and mix the ingredients thoroughly.
Strain the cocktail into a chilled martini glass.
Using the kitchen torch or a lighter, gently toast the top of the marshmallow until it becomes gooey and lightly charred.
Carefully remove the marshmallow from the skewer and place it on the rim of the martini glass.
Serve immediately and enjoy!