• Lightly grease the bottom and sides of an 8-inch or 9-inch square pan with butter.
• Dust powdered sugar over the pan, moving the pan around to ensure the entire bottom and sides are well covered. Shake off excess powdered sugar back into the bowl of powdered sugar. Set aside both the prepared pan and the reserve powdered sugar.
• In a medium bowl, add first ½ cup of cold water and gelatin powder. Stir once, gently, then set aside.
• Add granulated sugar and the second ½ cup of cold water to a large heavy saucepan over medium heat. Stir until the sugar is dissolved. Add the gelatin mixture to the pan and bring to a low boil.
• Remove from heat and allow to cool slightly at room temperature for a few minutes.
• Pour into a stand mixer (or large bowl, then use a hand mixer), and add the salt and vanilla extract. Beat at low-medium speed for about 10-15 minutes, until the mixture has become soft and slightly fluffy, and until it has almost doubled in size.
• Pour the marshmallow mixture into the prepared square baking pan.
• Allow the marshmallow mixture to cool in the pan at room temperature for at least 4 hours. It will be ready when you can touch the marshmallow and it won’t stick to your fingers. This can take anywhere from 4-8 hours, depending on the temperature and humidity in your home.
• Once set, cut the marshmallow block into 1” to 1½” squares. Roll squares gently into the reserve powdered sugar, covering all sides of the marshmallow squares. Add more powdered sugar as needed.
• Serve immediately, or store in an airtight container. Marshmallows should keep at room temperature for up to 3 days.
Notes
Makes 18 large marshmallows, or 24-30 small marshmallows