Line a small tray with parchment or a silicone mat.

Line an 8×8-inch square tin with parchment, allowing a 1-inch overhang on all sides. Spray with nonstick spray. Set aside until ready to use.

Pour 120 milliliters (1/2 cup) water into a large mixing bowl (if using a hand mixer), or the bowl of a stand mixer. Sprinkle the gelatin evenly over the water. Set aside.

Combine granulated sugar, corn syrup, remaining water, and kosher salt in a large, heavy-bottomed stock pot. Bring to a boil and boil, without stirring, until syrup reaches 240° F / 116° C on a candy thermometer.

Carefully pour hot syrup over gelatin. Mix on high speed for 2-3 minutes, until mixture begins to thicken.

Add the vanilla bean paste and continue mixing on high speed until very thick and voluminous, about 8-9 minutes more.

With an oiled rubber spatula, scrape marshmallow mixture into prepared tin.

Loosely cover with a well-oiled sheet of clingfilm/plastic wrap or aluminum foil, taking care not to touch the marshmallow. Allow to set until firm, at least 4 hours or overnight.

Cutting and Coating:

Cover a large chopping board with a sheet of parchment. Dust generously with cornflour.

Turn marshmallow slab out onto dusted surface. Peel away the parchment, then dust the top with more cornflour.

With a well-oiled 2 1/2-inch ghost cookie cutter, cut the slab into ghost shapes.

Toss each ghost-shaped marshmallow in additional cornflour.

With a pastry brush or your fingertips, brush away any excess powder. Arrange on prepared tray.

With a food safe paintbrush, dot each ghost with two black gel food coloring eyes and an oval-shaped mouth.

Store ghost marshmallows in an airtight container at room temperature for up to 1 month.