Add the champagne into the standing mixer bowl. Pour the gelatin on top of the water and mix with a whisk or fork to combine. Allow to bloom while making the sugar syrup.
Pour sugary, corn syrup, and sugar into a heavy bottomed saucepan. Mix until combined.
Using a pastry brush dipped in water, wipe down the sides of the pan to remove any lingering sugar crystals.
Heat sugar syrup mixture over medium high heat for about 10-20 minutes, until the mixture reaches 245 -250 degree fahrenheit. Do not mix the syrup while it heats up. This can cause crystallization of the sugar and ruin the marshmallows.
Once it hits the correct temperature, remove the sugar syrup from the heat.
Turn on the standing mixture to low and start mixing the bloomed champagne gelatin. While it’s mixing, slowly pour the sugar syrup down the sides of the bowl. The mix can splatter and it is very hot, so be careful when pouring.
Slowly increase the speed to medium high and add the vanilla. Beat for 5-10 minutes until thick and glossy.
Pour the mix into the prepared pan. If doing two colors, pour half the mix into a prepared pan and working quickly color the second half, mix until combined, and then pour into the second half of the pan.
Loosely cover with plastic wrap, making sure it doesn’t touch the marshmallow mixture. Let dry at least 6 hours or overnight.
When ready to cut, mix together powdered sugar and cornstarch.
Remove marshmallow from pan onto a surface lightly covered in the powdered sugar/cornstarch mixture.
Using a sharp knife or scissors, cut the marshmallows into desired shapes. Lightly coat the cut marshmallows in the cornstarch/powdered sugar mixture.
Enjoy! These marshmallows can be stored in an airtight container up to a week.