Homemade marshmallows

Grease a 9 by 13 inch pan with no-stick spray and sift in the quarter cup each of cornstarch and 10X sugar for total coverage; save the leftover powder.

Put a cup of cold water in the stand mixer bowl and sprinkle the three packets of gelatin over the surface without stirring; leave 5 minutes.

Stir together half a cup of water, 340 g granulated sugar and 60 g light corn syrup in a tall narrow vessel or saucepan.

Cook over medium heat to 240F, checking the centre with an instant-read thermometer.

Just shy of 240, fit the whisk and with the mixer on low drizzle the syrup down the side into the gelatin, avoiding the whisk.

Whip on high until very thick and fluffy and the bowl is lukewarm, 13 to 14 minutes; drop to half speed and add the vanilla.

Transfer quickly to the pan and smooth with a greased offset spatula; dust the top with the remaining sugar and starch.

Set uncovered at room temperature at least three hours.

Cut into cubes with a greased pizza cutter; store airtight with a desiccant pack.