Mix gelatin with 1/2 cup water in a small bowl with the vanilla. Set aside.

Combine the remaining 1/2 cup water, granulated sugar, corn syrup and salt in a medium saucepan. Cook over medium heat, stirring with a fork, until the syrup begins to simmer around the edges about 5 mins. Then increase to medium-hi and clip on a candy thermometer.

Cook without stirring to 250 degrees, about 5 mins.

Move thermometer to your kitchen aid mixing bowl and pour in the hot syrup.

Cool to 212 degrees about 6 mins.

Add the gelatin.

Mix on low speed with the whisk attachment for 1 minute.

Then mix on medium -hi until it triples in volume:10 mins.

On low, add the melted butter. Return to med-hi and beat a few more seconds.

Scrape this into a greased 8 inch pan.

Cover with foil and chill in fridge 2 hours.

When ready to cut, sift confectioners' sugar over the marshmallow, invert onto a board or counter and sprinkle with more sugar. Cut with a large chef's knife. Use sugar on the exposed surfaces so it is not too sticky.

Store in a parchment lined container.

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