Make the marshmallows

If you are using the vanilla bean, split bean on a cutting board with a sharp knife and scrape each edge to remove the seeds.

In a small bowl, add 4 oz water and vanilla bean (or vanilla extract if that is what you are using). Sprinkle gelatin on top.

Add the remaining ½ cup (4 ounces) water, corn syrup, sugar, and salt in a 3-quart stainless steel pot and set over medium heat.

Stir mixture with a fork until bubbling, about 5 minutes, then increase heat to medium-high. Clip on a digital thermometer and cook, without stirring, until the clear syrup registers 250°F, about 5 minutes.

Transfer the thermometer to the bowl of a stand mixer and pour in the hot syrup all at once, scraping the pot with a heat-resistant spatula. Cool to exactly 212°F, about 6 minutes. Add gelatin. With the whisk attachment, mix on low speed until gelatin is melted, then increase to medium-high and whip until thick, snowy white, roughly tripled in volume, and beginning to ball up around the whisk, about 10 minutes. Reduce the speed to low, add melted butter, return to medium-high, and beat for a few seconds more.

Scrape the creamy marshmallows into a lightly greased 8-inch square baking pan, spreading it into an even layer. Cover with foil and refrigerate until firm, about 2 hours (or let stand overnight at room temperature).

Cut the marshmallows:

Sift some powdered sugar over the marshmallow, invert onto a cutting board, and pry it loose with your fin-gers. Rub powdered sugar over the sticky candy, then use a large chef's knife to cut six 1½-inch-wide strips.

Working with 2 or 3 strips at a time, cut into 1½-inch cubes and tumble in a large bowl with the remaining powdered sugar.

Once the marshmallows are coated, transfer to an airtight container, with wax paper between each layer. Store for up to 3 weeks at room tempera-ture, or freeze for up to 6 months.