Pour 1/2 cup cold water into the bowl of your stand mixer. Sprinkle all 3 envelopes of gelatin over the surface and let it sit undisturbed for 10 minutes. It will absorb the water and thicken into something almost jelly-like — that’s exactly what you want.

Line a 9×9-inch baking pan with oiled plastic wrap, making sure it covers the bottom and sides. Set it right next to your mixer so you’re not scrambling when the mixture is ready.

In a saucepan, combine the granulated sugar, honey, and 1/4 cup water. Bring to a boil, stirring until the sugar dissolves. Once boiling, cook for 1 minute. For best results, use a thermometer — you’re aiming for 240-245 degrees F. See the notes below for climate adjustments.

Pour the boiling syrup into the bloomed gelatin and immediately beat on high speed with an electric mixer. Add the salt. Beat for a full 12 minutes — the mixture will go from thin and watery to thick, glossy, and brilliantly white. In the last 30 seconds, add the vanilla flavoring.

Lightly oil your hands and use them (or an oiled spatula) to scrape the marshmallow mixture into the prepared pan and spread evenly. Press another piece of oiled plastic wrap directly onto the surface. Let it sit at room temperature for at least 2 hours.

Dust a cutting board with powdered sugar. Turn the marshmallow slab out onto the board and peel away the plastic wrap. Dust the top generously with more powdered sugar. Use scissors or a greased knife to cut into 12 equal pieces. Dredge each marshmallow on all sides in powdered sugar so they don’t stick. Store in an airtight container at room temperature.