Grease and powder an 8×8 glass baking dish with the butter and 1-2 tablespoons of powdered sugar, making sure it is entirely coated. In the bowl of a stand mixer, combine the gelatin and cup of cold water, and set aside.

In a large saucepan, combine granulated sugar, corn syrup, salt, and water. Stir this mixture on medium-low heat until all the sugar has dissolved, and then bring to a boil. Once boiling, turn down the heat to medium-high and don’t stir until it reaches 240°F. (If you don’t have a candy thermometer, cook until the mixture turns into a pliable, gel-like ball when placed in cold water. You will know your mixture is arriving at the proper temperature as the bubbles become viscous and slow to pop.)

Pour the syrup gently into the gelatin and begin by mixing on low speed for about 5 minutes. Once it starts to thicken, separate in half. Add red food dye to one half. Turn the speed up to high until it has doubled in size and becomes thick. Pour into the baking dish. Mix the next half with blue food dye, and mix on high until doubled in size and thick. Pour on top of the red marshmallow layer. Allow the marshmallows to set for 8 hours or overnight.

Once the marshmallow has set, dust a cutting board or pan with powdered sugar and gently pull out the marshmallow mold. Use a greased star cookie cutter to make star-shaped marshmallows. Use a sharp knife or pizza cutter to cut the remaining mold into small marshmallows. Dust all of the sticky sides in powdered sugar, and store in an airtight bag or container.

To make a red, white, and blue s'more, roast your star mallow and place on a graham cracker with the white chocolate. (Feel free to cut your star marshmallow in half if desired.) Enjoy this ooey-gooey, festive treat!