Place the gelatin into the bowl of a stand mixer along with 1/2 cup of the water. This is called sponging. Have the whisk attachment standing by.

In a small saucepan combine the remaining 1/2 cup water, granulated sugar, corn syrup and salt. Place over medium heat until the sugar has dissolved. Do not let it boil at this stage.

Clip a candy thermometer onto the side of the pan and continue to cook until the mixture reaches 240°F, roughly 15 to 20 minutes, maybe more. You are aiming to reach soft ball stage on the thermometer. (I strongly recommend watching the video above for more detailed instruction)

Once the mixture reaches this temperature, immediately remove from the heat.

Turn the mixer on low speed and, while running, slowly pour the sugar syrup down the side of the bowl into the gelatin mixture. Once you have added all of the syrup, increase the speed to high. Continue to whip until the mixture becomes very thick and is lukewarm when you touch the bottom of the bowl, approximately 12 to 14 minutes.

For the Birthday Cake Marshmallows: Add the vanilla extract, almond extract, sprinkles and a tiny drop of food coloring during the last minute of whipping. While the mixture is whipping prepare the pans as follows.

For the Chocolate Marshmallows: Add the cocoa powder during the last minute of whipping. While the mixture is whipping prepare the pans as follows.

For the Mint Chocolate Chip Marshmallows: Add the mint extract, a tiny drop of green coloring and the chocolate chips during the last minute of whipping. Add the chips at the very last minute as the heat of the mixer can melt the chocolate. While the mixture is whipping prepare the pans as follows.

Combine the confectioners' sugar and cornstarch in a small bowl. Lightly grease a 8 x 8-inch (or 7 x 11-inch) baking pan with flavorless oil. Sift the sugar and cornstarch mixture and move around to completely coat the bottom and sides of the pan. Return the remaining mixture to the bowl for later use.

Grease a spatula, and even your hands, because believe me: this is sticky stuff.

When the marshmallow are ready, work QUICKLY and scrape the mixture into the prepared pan, using your spatula for spreading evenly into the pan. Dust the top with enough of the remaining sugar and cornstarch mixture to lightly cover. Reserve the rest for later.

Allow the marshmallows to sit uncovered for at least 4 hours and up to overnight. They need to be exposed to the air to form a skin.

After this time, turn the marshmallows out of the pan and allow the other side to be exposed to the air for another 4 hours.

On a cutting board, cut the marshmallows into squares using a pizza wheel or lightly oiled knife. Once cut, lightly dust all sides of each marshmallow with the remaining sugar mixture, using additional if necessary. (This sugar mix will keep the marshmallows dry and stop them from sticking together)

Store in an airtight container for up to 3 weeks.