Stir gelatin into water in a small bowl. Microwave for 30 seconds.
While that's in the microwave, pour your honey into a stand mixer mixing bowl. Add vanilla and the warm gelatin mixture.
Blend with the whisk attachment for 12-15 minutes until the mixture is white and fluffy and has quadrupled in size.
Coat a casserole dish with cornstarch.
Scoop marshmallow mixture into an oiled and well-starched casserole dish and smooth top so it's level with a spatula. Let it sit for a minimum of 6 hours. Overnight is best. It will be sticky but spongy to the touch when it's done.
Turn out onto a surface dusted with cornstarch.
Slice into desired size. Store in a plastic bag in the fridge.
Please note that the nutrition data below is a ballpark figure. Exact data is not possible.