Generously grease a 9x13 inch pan with coconut oil or butter. Then, dust it heavily with sifted powdered sugar to prevent the marshmallows from sticking.
2 tbsp coconut oil or softened butter
Combine 1/2 cup of water and the gelatin. Let it sit for about 5 minutes until it becomes thick and gelatinous then add to bowl of a stand mixer, if using, or a large bowl for mixing.
1 cup water, 3 packets unflavored gelatin
In a medium saucepan, combine the remaining 1/2 cup of water, granulated sugar, corn syrup, and salt. Heat it over medium heat until the sugar dissolves and the let the mixture gently boil until it reaches 240°F on a candy thermometer.
1 1/2 cups granulated sugar, 1 cup light corn syrup, 1/4 teaspoon salt, 1 cup water
With your stand mixer on low speed, slowly pour the hot sugar syrup in a steady slow stream close to the edge of the bowl or down the edge into the bloomed gelatin. Be very careful here as the sugar is very hot and will burn you if it gets on you.NOTE: If you are using a hand mixer, pour the gelatin and sugar syrup in first and then mix on low until all the ingredients are combined. Add the vanilla extract and vanilla bean paste, increase the mixer speed to high and beat for about 10 minutes until the mixture becomes thick and fluffy and the mixing bowl is cool to the touch.
2 teaspoons vanilla extract, 1 tbsp vanilla bean paste
Quickly pour the mixture into the prepared pan, using a spatula to smooth the top. Dust with more powdered sugar to prevent sticking. Allow the marshmallow mixture to sit uncovered at room temperature for at least 4 hours, or overnight, to set. Once set, turn the marshmallows onto a cutting board dusted with powdered sugar. Use a greased knife or cookie cutters to cut the marshmallows into your desired shapes. Roll each piece in more powdered sugar to coat.