Here is Jason Parsons, of Peller Estates Winery Restaurant in Niagara-on-the-lake, recipe for icewine marshmallows.
¾ CUP ICEWINE
3 ENVELOPES UNFLAVOURED GELATIN
¾ CUP WATER
2 CUPS GRANULATED SUGAR
2/3 CUP CORN SYRUP
¼ TSP VANILLA EXTRACT
Place icewine in a small saucepan over medium heat and simmer until reduced to 4 tablespoons, watching closely at the end to prevent scorching; cool.
Pour the 1/2 cup of cold water into the bowl of a stand mixer fitted with a whisk attachment. Sprinkle the gelatin over the water and let it stand for 10 minutes.
Meanwhile, mix the sugar, corn syrup, remaining water, and the icewine syrup. Bring to a boil and cook until the sugar reaches soft-ball stage (240º F).
Turn on the stand mixer to a low setting. Slowly pour in the hot sugar mixture, allowing the sugar to run down the side of the bowl. Add the salt and turn up the mixer to the highest speed. Beat for 12 to 15 minutes, until the mixture is fluffy and soft. It should hold soft peaks. Add the vanilla and beat for a minute longer.
Pour the mixture into a 9 x 9-inch cake pan that has been greased with oil. Using slightly wet hands, flatten out the marshmallow. Allow to set for at least 2 hours in a cool dry area. (Do not place in the refrigerator.) Once the marshmallow is firm, remove from the pan. Cut into even squares with a lightly oiled knife and toss each square in icing sugar to coat.